Re: [EVDL] EV Digest, Vol 90, Issue 36

[Lawrence Winiarski via EV]

Isn't  "Wide Band Noise" what RF guys overcome every day?   The reason you tune 
a radio is to ignore the 50 million otherchannels and the 
sun/jupiter/everyelectronicdevice known to man and concentrate on your own..
I can use my cell phone in my EV just fine.   If noise was really 
insurmountable, then I wouldn't be able to do that.

Seems to me that with enough selectivity over enough time, you can ignore every 
bit of noise known to man.
As I said the Ham guys can pick out signal in signal to noise ratios of -120db. 
 That's 12 orders of magnitude and they can detecta walkie/talkie on the 
other side of the globe.   It's amazing.   Sure it's only a few bits/min, but 
the point is that it IS doable.

It requires a different mindset than just straight digital manipulation.   You 
accept error rates and deal with them using math.



   On Tuesday, April 28, 2020, 9:58:47 PM PDT, Offgrid Systems via EV 
 wrote:  
 
 Yeah I'm gonna agree with Lee here. I've been thinking about this for 
years also, going as far as testing some ac powerline comm chips adapted 
to DC power busses. I found it's impossible with all the noise coming 
from the drive on an EV.  But Lee, you don't even need a spectrum 
analyser, just fire up your EV drive train, looking at any of the phases 
with a oscilloscope. It's wide band noise, and the motor control is 
modulating to operate the motor, but with sinewave drives, or even the 
old PWM drives, there is noise during the entire cycle, and the only way 
you get a quiet time is if you actually shut off and short the motor for 
a brief period. But if you do that there will be high peak currents that 
will not be good for the efficiency of the drive. If reliability is the 
key, you will not want to use the DC busses, unless it's a low noise 
application, and you can control and build all of the power devices, 
like maybe a powerwall with a pure sinewave inverter, and you make the 
charger (solar charge controller) and the inverter. But for motor 
control, it's a difficult problem to solve.

Tim Economu

On 4/28/2020 6:48 PM, ev-requ...@lists.evdl.org wrote:
> It sounds easy; but put a spectrum analyzer on your battery leads to see
> what's*really*  there. I think you'd be shocked at the noise level.
>
>> There are a few clever tricks you can employ. During charging, you can
>> have the charger pause for a regular "moment of silence" in which the
>> BMS can communicate quickly and in the clear without having to "shout"
>> over the charger PWM. Perhaps the same thing could occur to a lesser
>> extent with the inverter.
> Same as above. Are you going to design a special charger that must be
> used with your BMS?
>
> There are lots of solutions that work*some*  of the time. There are a
> few that work*most*  of the time. But it gets damnably difficult to find
> schemes that work*all*  of the time.
>
> The problem is that a BMS is a safety system that you want to work*all*  
> of the time.
>
> Lee Hart

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Re: [EVDL] EV Digest, Vol 90, Issue 36

[Offgrid Systems via EV]

Yeah I'm gonna agree with Lee here. I've been thinking about this for 
years also, going as far as testing some ac powerline comm chips adapted 
to DC power busses. I found it's impossible with all the noise coming 
from the drive on an EV.  But Lee, you don't even need a spectrum 
analyser, just fire up your EV drive train, looking at any of the phases 
with a oscilloscope. It's wide band noise, and the motor control is 
modulating to operate the motor, but with sinewave drives, or even the 
old PWM drives, there is noise during the entire cycle, and the only way 
you get a quiet time is if you actually shut off and short the motor for 
a brief period. But if you do that there will be high peak currents that 
will not be good for the efficiency of the drive. If reliability is the 
key, you will not want to use the DC busses, unless it's a low noise 
application, and you can control and build all of the power devices, 
like maybe a powerwall with a pure sinewave inverter, and you make the 
charger (solar charge controller) and the inverter. But for motor 
control, it's a difficult problem to solve.


Tim Economu

On 4/28/2020 6:48 PM, ev-requ...@lists.evdl.org wrote:

It sounds easy; but put a spectrum analyzer on your battery leads to see
what's*really*  there. I think you'd be shocked at the noise level.


There are a few clever tricks you can employ. During charging, you can
have the charger pause for a regular "moment of silence" in which the
BMS can communicate quickly and in the clear without having to "shout"
over the charger PWM. Perhaps the same thing could occur to a lesser
extent with the inverter.

Same as above. Are you going to design a special charger that must be
used with your BMS?

There are lots of solutions that work*some*  of the time. There are a
few that work*most*  of the time. But it gets damnably difficult to find
schemes that work*all*  of the time.

The problem is that a BMS is a safety system that you want to work*all*  
of the time.


Lee Hart


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Re: [EVDL] Communicating over "mains" (Was: Minibms?)

[Lawrence Winiarski via EV]

So by SAFETY system, what do you want to do?   I guess I only see two things
A.   Stop the Car.B.   Stop the Charger.
Suppose you queried 1 time per second.  Suppose you got 3600 good readings then 
ONE bad one (or failed to get one), then started getting good ones again, would 
you really want to
A.  Stop the car
B.  Start and stop the charger?
I would think that you could tolerate some error rate with a little bit of 
software intelligence such as
IF last readings were near limits then execute safety stop
IF last reading was well within tolerance, ignoreIF Failed to get reading for N 
consecutive seconds the execute safety stop
Would this really be so unreasonable or unsafe?



On Tuesday, April 28, 2020, 9:10:40 PM PDT, Lee Hart via EV 
 wrote:  
 
 Peri Hartman via EV wrote:
> The BMS for each cell would normally be quiet and only send something when
> prompted by a central BMS component.

I think it is important to consider just what you want a BMS to do.

- Is it just there to provide feedback on what each cell is doing?
    (battery MONITORING system)
- Is it there to actively balance cells?
    (battery BALANCING system)
- Is it a safety system, there to prevent damage and fires?
    (battery SAFETY system)

These are three very different devices, with completely different design 
requirements.

When you talk about systems with a computer on every cell, and CAN bus 
networking with TCP/IP, you're talking about a Monitoring system. It's 
supposed to provide accurate real-time data on things like cell 
voltages, currents, and temperatures. It probably needs a fancy display 
(blinkinlights), and data logging (pretty charts and graphs).

Such a system is necessarily complicated, with correspondingly high cost 
and low reliability. It will need hundreds, perhaps thousands of parts, 
and so have many failure modes. Given the heavy dependence on software, 
it will be nearly impossible to predict what happens when it fails.

And, it's going to be the exact opposite of a safety system.

Lee Hart
-- 
If happiness is on your mind, here's a daily list to find:
    - something to do
    - something to look forward to
    - someone to love
    - someone to take good care of
    - and misbehave, just a little
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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Re: [EVDL] .ie Tips for driving an electric car> (?laughable or sad?)

[Peri Hartman via EV]

I think they should write instructions on how to make toast, too. Why 
stop when you're so talented ?

Peri

-- Original Message --
From: "evln via EV" 
To: ev@lists.evdl.org
Cc: "evln" 
Sent: 28-Apr-20 9:37:13 PM
Subject: [EVDL] .ie Tips for driving an electric car> (?laughable or 
sad?)





 (ireland media outlet)
https://intallaght.ie/tips-for-driving-an-electric-car-step-by-step/
Tips for driving an electric car, step by step
2020-04-29 ... make sure the car is not plugged in. If so, take a look at
charge level (Normally, you have some kind of LED ‘sneak’ so you can see it
from the outside ... Do not leave the door open longer than important. – Do
not press the start button until you are really going to start driving to
avoid draining the battery prematurely. – Turn off consumables (interior
lights, exterior lights, radio, air conditioning) ... (?idiotic?)
https://i2.wp.com/intallaght.ie/wp-content/uploads/2020/04/Tips-for-driving-an-electric-car-step-by-step.jpg


+
https://intallaght.ie/the-electric-bicycle-convertible-into-a-cargo-bike-that-can-carry-180-kilos-of-weight/
The electric bicycle convertible into a cargo bike that can carry 180 Kilos
of weight
2020-04-29 ... Bicycles are one-person vehicles, designed to transport a
single person. Some models offer a small basket to carry the backpack or a
small bag, and little else ...
https://i1.wp.com/intallaght.ie/wp-content/uploads/2020/04/The-electric-bicycle-convertible-into-a-cargo-bike-that-can.jpg




For EVLN EV-newswire posts view:
http://www.evdl.org/archive/
https://mail-archive.com/ev@lists.evdl.org/maillist.html


{brucedp.neocities.org}

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Re: [EVDL] Communicating over "mains" (Was: Minibms?)

[Peri Hartman via EV]

See below.

-- Original Message --
From: "Lee Hart" 
To: "Peri Hartman" ; "Electric Vehicle Discussion 
List" 

Sent: 28-Apr-20 9:10:37 PM
Subject: Re: [EVDL] Communicating over "mains" (Was: Minibms?)


Peri Hartman via EV wrote:

The BMS for each cell would normally be quiet and only send something when
prompted by a central BMS component.


I think it is important to consider just what you want a BMS to do.

- Is it just there to provide feedback on what each cell is doing?
(battery MONITORING system)
- Is it there to actively balance cells?
(battery BALANCING system)
- Is it a safety system, there to prevent damage and fires?
(battery SAFETY system)
Doesn't matter. It can still be handled by a poll from a master. The 
point I was trying to make is to find a way to not have a bunch of data 
collisions and keep the comm part of the system simple. Since the comm 
is fast, it would be easy to round-robin monitor all cells 100s if not 
1000s of times a second.


By "simple" extension of the protocol, one could add instructions back 
to the cells. As long as the master is in control, there won't be 
collisions.


You could have an interrupt based system where cells try to send to the 
master when an emergency condition happens. But I don't think there's 
any need for that. If the master is working, it will poll the cell soon 
enough to respond to the emergency. If the master is not working, it 
won't respond to the interrupt, anyway.


I think the real issue is how to handle a failure of the comm system or 
the master. The cells need to have some sort of built-in timer that 
shuts them down if the master fails to poll them. Or maybe there are 
some other, better ways to do that.


In regard to your three example flavors, it seems that for a robust BMS 
each individual cell monitor must do all three. I'm out of my domain 
here, but can't balancing be handled by checking cell voltage ? That is, 
when charging, slow the charge current (shunt the excess current) as the 
voltage reaches the cut-off (and opposite for discharging). What needs 
to be done for safety ? I presume that's primarily keeping current 
within limits and watching the temperature.


Peri



These are three very different devices, with completely different design 
requirements.

When you talk about systems with a computer on every cell, and CAN bus 
networking with TCP/IP, you're talking about a Monitoring system. It's supposed 
to provide accurate real-time data on things like cell voltages, currents, and 
temperatures. It probably needs a fancy display (blinkinlights), and data 
logging (pretty charts and graphs).

Such a system is necessarily complicated, with correspondingly high cost and 
low reliability. It will need hundreds, perhaps thousands of parts, and so have 
many failure modes. Given the heavy dependence on software, it will be nearly 
impossible to predict what happens when it fails.

And, it's going to be the exact opposite of a safety system.

Lee Hart
-- If happiness is on your mind, here's a daily list to find:
- something to do
- something to look forward to
- someone to love
- someone to take good care of
- and misbehave, just a little
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, http://www.sunrise-ev.com


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[EVDL] .ie Tips for driving an electric car> (?laughable or sad?)

[evln via EV]

 (ireland media outlet)
https://intallaght.ie/tips-for-driving-an-electric-car-step-by-step/
Tips for driving an electric car, step by step
2020-04-29 ... make sure the car is not plugged in. If so, take a look at
charge level (Normally, you have some kind of LED ‘sneak’ so you can see it
from the outside ... Do not leave the door open longer than important. – Do
not press the start button until you are really going to start driving to
avoid draining the battery prematurely. – Turn off consumables (interior
lights, exterior lights, radio, air conditioning) ... (?idiotic?)
https://i2.wp.com/intallaght.ie/wp-content/uploads/2020/04/Tips-for-driving-an-electric-car-step-by-step.jpg


+
https://intallaght.ie/the-electric-bicycle-convertible-into-a-cargo-bike-that-can-carry-180-kilos-of-weight/
The electric bicycle convertible into a cargo bike that can carry 180 Kilos
of weight
2020-04-29 ... Bicycles are one-person vehicles, designed to transport a
single person. Some models offer a small basket to carry the backpack or a
small bag, and little else ...
https://i1.wp.com/intallaght.ie/wp-content/uploads/2020/04/The-electric-bicycle-convertible-into-a-cargo-bike-that-can.jpg




For EVLN EV-newswire posts view:
 http://www.evdl.org/archive/
https://mail-archive.com/ev@lists.evdl.org/maillist.html


{brucedp.neocities.org}

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Re: [EVDL] Designing a lithium pack using reclaimed A123 cells.

[Lawrence Rhodes via EV]

 These are the cells: ANR26650M1A FS31-1A8 FH1010823-R-2 Lawrence Rhodes
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Re: [EVDL] Communicating over "mains" (Was: Minibms?)

[Lee Hart via EV]

Peri Hartman via EV wrote:

The BMS for each cell would normally be quiet and only send something when
prompted by a central BMS component.


I think it is important to consider just what you want a BMS to do.

- Is it just there to provide feedback on what each cell is doing?
(battery MONITORING system)
- Is it there to actively balance cells?
(battery BALANCING system)
- Is it a safety system, there to prevent damage and fires?
(battery SAFETY system)

These are three very different devices, with completely different design 
requirements.


When you talk about systems with a computer on every cell, and CAN bus 
networking with TCP/IP, you're talking about a Monitoring system. It's 
supposed to provide accurate real-time data on things like cell 
voltages, currents, and temperatures. It probably needs a fancy display 
(blinkinlights), and data logging (pretty charts and graphs).


Such a system is necessarily complicated, with correspondingly high cost 
and low reliability. It will need hundreds, perhaps thousands of parts, 
and so have many failure modes. Given the heavy dependence on software, 
it will be nearly impossible to predict what happens when it fails.


And, it's going to be the exact opposite of a safety system.

Lee Hart
--
If happiness is on your mind, here's a daily list to find:
- something to do
- something to look forward to
- someone to love
- someone to take good care of
- and misbehave, just a little
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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Re: [EVDL] Communicating over "mains" (Was: Minibms?)

[Peri Hartman via EV]

Since this is a well defined system, in the sense that the composition 
of components is normally static, it seems reasonable to have a 
centrally controlled communication protocol. The BMS for each cell would 
normally be quiet and only send something when prompted by a central BMS 
component. You can imagine building some additonal layers of safety such 
as the cell automatically shutting down if no poll comes from the 
central BMS for some period of time.


TCP/IP is probably overkill but it's well established and could be used 
to ensure fail-safe communications. If one is to embed a radio in each 
cell with some logic processing, it seems a small extension to add the 
bottom layers of comm.


I suppose I'm regurgitating what's been done with wired systems, but it 
seems straight forward enough.


Peri

-- Original Message --
From: "Bill Dube via EV" 
To: ev@lists.evdl.org
Cc: "Bill Dube" 
Sent: 28-Apr-20 7:46:26 PM
Subject: Re: [EVDL] Communicating over "mains" (Was: Minibms?)


Indeed, you would have to design the entire system, inverter, charger, etc. to 
accommodate this communication scheme. Not an "add-on" type BMS my any means.

All of the "noise" comes from the components, and the designers have control over each 
and every component in that environment. A regularly spaced, "moment of silence" is not 
difficult to coordinate if you talk to every component with the CAN bus. It can be so short that 
the user will not be able to sense that it has happened.

You can also pick your communication band without a care, because you are on a private 
"network". Perhaps have the cell BMS sweep to find a band that works best 
during commissioning.

The input caps might block the cell BMS RF signal from _entering_ the inverter 
(or charger). However, the signal will still be present and detectable as a 
_current_ in the traction wiring, rather than as a voltage on the input 
terminals of the inverter (or charger.)

Bill D.

On 4/29/2020 1:48 PM, Lee Hart via EV wrote:

Bill Dube via EV wrote:

I have thought about doing this for perhaps 20 years. It may well be
possible to communicate via the traction conductors. It is probably
worth the effort to do so because it would allow you to incorporate the
BMS in the cell. Sealing the BMS inside each cell could be very useful,
especially from a warranty/liability angle. The cell manufacturer would
love to have a log of the SOC history of the cell.


It is certainly possible. The problem is whether it is practical.

If you are an automaker, with control over every aspect of the vehicle, the situation may 
be manageable. You can pick a part of the RF spectrum for your BMS communications where 
you know (or create) a "hole" in the noise from the other parts of the vehicle.

You can also route your wiring so as not to create any "dead spots". When you 
don't have a controlled impedance (known capacitance and inductance in the wiring), RF 
systems will have peaks and nulls that can prevent certain locations from communicating, 
where moving it a foot down the wire either way works.

But I think the situation is nearly hopeless in an open-source hobby EV. It 
would boil down to trial and error, where the installer doesn't know what noise 
the pieces are producing, and can't do anything to change them, and can't 
change the RF spectrum that the BMS is trying to use.

That's why providing a separate communication channel is almost universal. It 
might be wired, or optical, or RF (not relying on the traction wiring to carry 
the signal). You have a far better chance of it working.


Communicating _to_ the BMS is simple. You have two VERY large
transmitters, the charger and the inverter. Simply frequency modulate
the pwm of the inverter and/or the charger and put an FM detector in
each BMS on the cell level. You turn the "noise" source into the
communication transmitter. Done.


That works if you designed the charger and inverter and BMS specifically to 
work together to do this.


Communication _from_ the cells is not quite as simple, but doable. Use
the by-pass circuit to talk to the outside world. Put a capacitor in
parallel with the by-pass resistor so that when you switch on the
resistor, you get a spike.


Perhaps; but the batteries themselves still have a huge equivalent capacitance. 
The charger and controller are also likely to have huge low-ESR filter 
capacitors across them, which try to short out any RF signals present.

It sounds easy; but put a spectrum analyzer on your battery leads to see what's 
*really* there. I think you'd be shocked at the noise level.


There are a few clever tricks you can employ. During charging, you can
have the charger pause for a regular "moment of silence" in which the
BMS can communicate quickly and in the clear without having to "shout"
over the charger PWM. Perhaps the same thing could occur to a lesser
extent with the inverter.


Same as above. Are you going to design a special charger that must be used with 
your BMS?

Re: [EVDL] Communicating over "mains" (Was: Minibms?)

[Bill Dube via EV]

Indeed, you would have to design the entire system, inverter, charger, 
etc. to accommodate this communication scheme. Not an "add-on" type BMS 
my any means.


All of the "noise" comes from the components, and the designers have 
control over each and every component in that environment. A regularly 
spaced, "moment of silence" is not difficult to coordinate if you talk 
to every component with the CAN bus. It can be so short that the user 
will not be able to sense that it has happened.


You can also pick your communication band without a care, because you 
are on a private "network". Perhaps have the cell BMS sweep to find a 
band that works best during commissioning.


The input caps might block the cell BMS RF signal from _entering_ the 
inverter (or charger). However, the signal will still be present and 
detectable as a _current_ in the traction wiring, rather than as a 
voltage on the input terminals of the inverter (or charger.)


Bill D.

On 4/29/2020 1:48 PM, Lee Hart via EV wrote:

Bill Dube via EV wrote:

I have thought about doing this for perhaps 20 years. It may well be
possible to communicate via the traction conductors. It is probably
worth the effort to do so because it would allow you to incorporate the
BMS in the cell. Sealing the BMS inside each cell could be very useful,
especially from a warranty/liability angle. The cell manufacturer would
love to have a log of the SOC history of the cell.


It is certainly possible. The problem is whether it is practical.

If you are an automaker, with control over every aspect of the 
vehicle, the situation may be manageable. You can pick a part of the 
RF spectrum for your BMS communications where you know (or create) a 
"hole" in the noise from the other parts of the vehicle.


You can also route your wiring so as not to create any "dead spots". 
When you don't have a controlled impedance (known capacitance and 
inductance in the wiring), RF systems will have peaks and nulls that 
can prevent certain locations from communicating, where moving it a 
foot down the wire either way works.


But I think the situation is nearly hopeless in an open-source hobby 
EV. It would boil down to trial and error, where the installer doesn't 
know what noise the pieces are producing, and can't do anything to 
change them, and can't change the RF spectrum that the BMS is trying 
to use.


That's why providing a separate communication channel is almost 
universal. It might be wired, or optical, or RF (not relying on the 
traction wiring to carry the signal). You have a far better chance of 
it working.



Communicating _to_ the BMS is simple. You have two VERY large
transmitters, the charger and the inverter. Simply frequency modulate
the pwm of the inverter and/or the charger and put an FM detector in
each BMS on the cell level. You turn the "noise" source into the
communication transmitter. Done.


That works if you designed the charger and inverter and BMS 
specifically to work together to do this.



Communication _from_ the cells is not quite as simple, but doable. Use
the by-pass circuit to talk to the outside world. Put a capacitor in
parallel with the by-pass resistor so that when you switch on the
resistor, you get a spike.


Perhaps; but the batteries themselves still have a huge equivalent 
capacitance. The charger and controller are also likely to have huge 
low-ESR filter capacitors across them, which try to short out any RF 
signals present.


It sounds easy; but put a spectrum analyzer on your battery leads to 
see what's *really* there. I think you'd be shocked at the noise level.



There are a few clever tricks you can employ. During charging, you can
have the charger pause for a regular "moment of silence" in which the
BMS can communicate quickly and in the clear without having to "shout"
over the charger PWM. Perhaps the same thing could occur to a lesser
extent with the inverter.


Same as above. Are you going to design a special charger that must be 
used with your BMS?


There are lots of solutions that work *some* of the time. There are a 
few that work *most* of the time. But it gets damnably difficult to 
find schemes that work *all* of the time.


The problem is that a BMS is a safety system that you want to work 
*all* of the time.


Lee Hart



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Re: [EVDL] Communicating over "mains" (Was: Minibms?)

[Lawrence Winiarski via EV]

Let me play devils advocate.    If it was so hard, then why does my cell 
phone/radio/satellite work?   They pickup microvolts out of the air and work 
pretty well.   I'm communicating my email to a tower 10 miles away.  I'm doing 
itwith 2 watts!   That's pretty amazing.

the bypass resistor can do 0.5-1 amp.  That's a non trivial signal to look for. 
 Now put it at a particular freq and give itenough cycles and look for it with 
an FFT in software and I'd guess it's going to be detectable.   Now addCRC for 
errors and viola.    

And if occasionally 1 out of 10 times you get a bad reading...who cares.  
It's a BMS.   It's not going to explode.Just make some annoying beep.   I can 
live with that.
The advantage is no wires.  No fire hazard.  Decent stats on the battery.
I'd say the wins outweigh the disadvantages.

Don't let the perfect be the enemy of the good.   Things change relatively slow 
in the battery world and a fewbad readings are probably acceptable.   In a 
master/slave system if the BMS doesn't respond to a query, thentreat it as a t  
fault.   Turn off the charger, or let the user know by beeping or blinking or 
something.  

 I think that the proof will be in someone doing it.   Perhaps I'm opotomistic, 
but  I have confidence that it would work.


   On Tuesday, April 28, 2020, 6:48:38 PM PDT, Lee Hart via EV 
 wrote:  
 
 Bill Dube via EV wrote:
> I have thought about doing this for perhaps 20 years. It may well be
> possible to communicate via the traction conductors. It is probably
> worth the effort to do so because it would allow you to incorporate the
> BMS in the cell. Sealing the BMS inside each cell could be very useful,
> especially from a warranty/liability angle. The cell manufacturer would
> love to have a log of the SOC history of the cell.

It is certainly possible. The problem is whether it is practical.

If you are an automaker, with control over every aspect of the vehicle, 
the situation may be manageable. You can pick a part of the RF spectrum 
for your BMS communications where you know (or create) a "hole" in the 
noise from the other parts of the vehicle.

You can also route your wiring so as not to create any "dead spots". 
When you don't have a controlled impedance (known capacitance and 
inductance in the wiring), RF systems will have peaks and nulls that can 
prevent certain locations from communicating, where moving it a foot 
down the wire either way works.

But I think the situation is nearly hopeless in an open-source hobby EV. 
It would boil down to trial and error, where the installer doesn't know 
what noise the pieces are producing, and can't do anything to change 
them, and can't change the RF spectrum that the BMS is trying to use.

That's why providing a separate communication channel is almost 
universal. It might be wired, or optical, or RF (not relying on the 
traction wiring to carry the signal). You have a far better chance of it 
working.

> Communicating _to_ the BMS is simple. You have two VERY large
> transmitters, the charger and the inverter. Simply frequency modulate
> the pwm of the inverter and/or the charger and put an FM detector in
> each BMS on the cell level. You turn the "noise" source into the
> communication transmitter. Done.

That works if you designed the charger and inverter and BMS specifically 
to work together to do this.

> Communication _from_ the cells is not quite as simple, but doable. Use
> the by-pass circuit to talk to the outside world. Put a capacitor in
> parallel with the by-pass resistor so that when you switch on the
> resistor, you get a spike.

Perhaps; but the batteries themselves still have a huge equivalent 
capacitance. The charger and controller are also likely to have huge 
low-ESR filter capacitors across them, which try to short out any RF 
signals present.

It sounds easy; but put a spectrum analyzer on your battery leads to see 
what's *really* there. I think you'd be shocked at the noise level.

> There are a few clever tricks you can employ. During charging, you can
> have the charger pause for a regular "moment of silence" in which the
> BMS can communicate quickly and in the clear without having to "shout"
> over the charger PWM. Perhaps the same thing could occur to a lesser
> extent with the inverter.

Same as above. Are you going to design a special charger that must be 
used with your BMS?

There are lots of solutions that work *some* of the time. There are a 
few that work *most* of the time. But it gets damnably difficult to find 
schemes that work *all* of the time.

The problem is that a BMS is a safety system that you want to work *all* 
of the time.

Lee Hart

-- 
If happiness is on your mind, here's a daily list to find:
    - something to do
    - something to look forward to
    - someone to love
    - someone to take good care of
    - and misbehave, just a little
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
___

Re: [EVDL] EV Digest, Vol 90, Issue 34

[Mr. Sharkey via EV]

Tim;

I'm glad you posted this. I didn't know how much attention your 
desired, but wanted the members of the list to recognize your contribution.


We haven't met or talked, but I'm sure if we did, we'd discover that 
we have only a degree or two of separation in the RE industry, and 
probably other associations as well. And yes, I do own and use 
several makes and models of equipment that you either designed or 
helped bring to market. I've certainly done repairs to some of them, 
keeping them useful for myself and others.


My hope is that you'll find the time and interest to continue to 
participate in the EVDL, it has a legacy we can all be proud to support.


-Sharkey

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Re: [EVDL] Communicating over "mains" (Was: Minibms?)

[Lee Hart via EV]

Bill Dube via EV wrote:

I have thought about doing this for perhaps 20 years. It may well be
possible to communicate via the traction conductors. It is probably
worth the effort to do so because it would allow you to incorporate the
BMS in the cell. Sealing the BMS inside each cell could be very useful,
especially from a warranty/liability angle. The cell manufacturer would
love to have a log of the SOC history of the cell.


It is certainly possible. The problem is whether it is practical.

If you are an automaker, with control over every aspect of the vehicle, 
the situation may be manageable. You can pick a part of the RF spectrum 
for your BMS communications where you know (or create) a "hole" in the 
noise from the other parts of the vehicle.


You can also route your wiring so as not to create any "dead spots". 
When you don't have a controlled impedance (known capacitance and 
inductance in the wiring), RF systems will have peaks and nulls that can 
prevent certain locations from communicating, where moving it a foot 
down the wire either way works.


But I think the situation is nearly hopeless in an open-source hobby EV. 
It would boil down to trial and error, where the installer doesn't know 
what noise the pieces are producing, and can't do anything to change 
them, and can't change the RF spectrum that the BMS is trying to use.


That's why providing a separate communication channel is almost 
universal. It might be wired, or optical, or RF (not relying on the 
traction wiring to carry the signal). You have a far better chance of it 
working.



Communicating _to_ the BMS is simple. You have two VERY large
transmitters, the charger and the inverter. Simply frequency modulate
the pwm of the inverter and/or the charger and put an FM detector in
each BMS on the cell level. You turn the "noise" source into the
communication transmitter. Done.


That works if you designed the charger and inverter and BMS specifically 
to work together to do this.



Communication _from_ the cells is not quite as simple, but doable. Use
the by-pass circuit to talk to the outside world. Put a capacitor in
parallel with the by-pass resistor so that when you switch on the
resistor, you get a spike.


Perhaps; but the batteries themselves still have a huge equivalent 
capacitance. The charger and controller are also likely to have huge 
low-ESR filter capacitors across them, which try to short out any RF 
signals present.


It sounds easy; but put a spectrum analyzer on your battery leads to see 
what's *really* there. I think you'd be shocked at the noise level.



There are a few clever tricks you can employ. During charging, you can
have the charger pause for a regular "moment of silence" in which the
BMS can communicate quickly and in the clear without having to "shout"
over the charger PWM. Perhaps the same thing could occur to a lesser
extent with the inverter.


Same as above. Are you going to design a special charger that must be 
used with your BMS?


There are lots of solutions that work *some* of the time. There are a 
few that work *most* of the time. But it gets damnably difficult to find 
schemes that work *all* of the time.


The problem is that a BMS is a safety system that you want to work *all* 
of the time.


Lee Hart

--
If happiness is on your mind, here's a daily list to find:
- something to do
- something to look forward to
- someone to love
- someone to take good care of
- and misbehave, just a little
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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[EVDL] Designing a lithium pack using reclaimed A123 cells.

[Lawrence Rhodes via EV]

It seems mini BMS is the BMS to use. At 72vdc what charger voltage and string 
size? Is it 21 or 22 cells in series? Should I use 21 cells to protect the 
controller. Or slightly undercharge 22 cells to protect the pack. Do chargers 
and BMS talk to each other? Is 5ah at 72v a lot of energy? Do controllers have 
a gray area or must you be right on the money? So many questions and worries 
now that I have enough batteries to get in trouble.  Lawrence Rhodes
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Re: [EVDL] Communicating over "mains" (Was: Minibms?)

[Lawrence Winiarski via EV]

Simple idea  as a start of discussion assuming an AVR on the BMS and a 
cap/comparator circuit to detect and 
amplify comm signal

Assumes each BMS has an "uniq NODE".

Monitor COM voltages at F1 hz.  Store.  
Analyze stored data for master signal  at F2 hz.   Decode and sync local clock 
to master clock.   

IF we have data to report, wait for TimeSlot for NODE, then send.   use use 
bypass resistor to send square wave at F3 hz  cycles, 


Messages would be sent using something like manchester coding and messages 
could be stretched across multiple time slots.
Messages would use something like CRC to guarantee validity.




   On Tuesday, April 28, 2020, 4:54:11 PM PDT, Lawrence Winiarski via EV 
 wrote:  
 
 Awesome. 

I like the idea of the transmitter in the charger, but it would also be cool to 
make it an add-on with an existing charger.   
 I would think you would want the frequency to be well off the freq of the 
charger switchers.   Any ideas on that?
Have any idea what the small signal impedance vs frequency is for lifepo4 100ah 
batteries?   I would think that batterieshave high impedance at high freq 
regardless of SOC.   Chemistry just doesn't happen that fast.

I think a possibility would be to have a synchronizing pulse sent from the 
"master" and use time slots for each bms slave 
to respond.  I would think that making the BMS as a slave saves energy too.   
It doesn't waste energy talking unless ithas too.



  On Tuesday, April 28, 2020, 4:38:16 PM PDT, Bill Dube via EV 
 wrote:  
 
 I have thought about doing this for perhaps 20 years. It may well be 
possible to communicate via the traction conductors. It is probably 
worth the effort to do so because it would allow you to incorporate the 
BMS in the cell. Sealing the BMS inside each cell could be very useful, 
especially from a warranty/liability angle. The cell manufacturer would 
love to have a log of the SOC history of the cell.

Communicating _to_ the BMS is simple. You have two VERY large 
transmitters, the charger and the inverter. Simply frequency modulate 
the pwm of the inverter and/or the charger and put an FM detector in 
each BMS on the cell level. You turn the "noise" source into the 
communication transmitter. Done.

Communication _from_ the cells is not quite as simple, but doable. Use 
the by-pass circuit to talk to the outside world. Put a capacitor in 
parallel with the by-pass resistor so that when you switch on the 
resistor, you get a spike. Again, you can transmit via FM using "spikes" 
generated by switching the by-pass on and off briefly.

There are a few clever tricks you can employ. During charging, you can 
have the charger pause for a regular "moment of silence" in which the 
BMS can communicate quickly and in the clear without having to "shout" 
over the charger PWM. Perhaps the same thing could occur to a lesser 
extent with the inverter.

Also, cells that are in a high SOC or low SOC have a high impedance, 
which would tend to make the BMS signal "louder". Since this is the most 
critical time for BMS communication, this helps quite a bit. During 
these times they can "scream" to the inverter to stop for a moment so 
they can give details about the problem.

Just a thought

     Bill D.

On 4/29/2020 9:35 AM, Lawrence Winiarski via EV wrote:
>> Because there are no "mains" in a vehicle.???
> Is it really "That" Noisy?   I suspect it is very doable, it's just that no 
> one has done it yet.The trick is probably using signal processing to get rid 
> of the noise and doing extremelylow bit rates, which is fine for a BMS.    
> Ham radio guys can send stuff over the entire earthon 10 watts using 
> techniques like jt65.   I expect they can deal with a little noise.   it's 
> justnot going to be trivial, but it would be doable.
>
> IMHO the main use for the BMS is in charging anyway.
>
>    On Tuesday, April 28, 2020, 2:12:26 PM PDT, Lee Hart 
> wrote:
>  
>  Lawrence Winiarski wrote:
>> Anyone know anything about data over powerlines?  Why can't the BMS
>> communicate over the mains?
> Because there are no "mains" in a vehicle.
>
> That said, it is possible to communicate via the DC power cables already
> connected to each cell. But this is an extremely noisy environment. It
> would require substantial filtering and protection to keep driving
> currents from trashing data transfers. Some chargers are also extremely
> noisy, and could block data transfers while charging.
>
> Lee


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An HTM

Re: [EVDL] Lincoln cancels using rivian> (fmc pulls a fakey, ?pr-hoopla?)

[EVDL Administrator via EV]

If Lincoln wants to continue selling cars in China, they'll need to develop 
some kind of EV.  AFAIK, they have little or no sales in Europe, and I doubt 
that they care much about US EV sales.  So it would probably make sense for 
them to form a partnership with one of the Chinese automakers.

David Roden - Akron, Ohio, USA
EVDL Administrator

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Re: [EVDL] Communicating over "mains" (Was: Minibms?)

[Lawrence Winiarski via EV]

Awesome. 

I like the idea of the transmitter in the charger, but it would also be cool to 
make it an add-on with an existing charger.   
 I would think you would want the frequency to be well off the freq of the 
charger switchers.   Any ideas on that?
Have any idea what the small signal impedance vs frequency is for lifepo4 100ah 
batteries?   I would think that batterieshave high impedance at high freq 
regardless of SOC.   Chemistry just doesn't happen that fast.

I think a possibility would be to have a synchronizing pulse sent from the 
"master" and use time slots for each bms slave 
to respond.  I would think that making the BMS as a slave saves energy too.   
It doesn't waste energy talking unless ithas too.



   On Tuesday, April 28, 2020, 4:38:16 PM PDT, Bill Dube via EV 
 wrote:  
 
 I have thought about doing this for perhaps 20 years. It may well be 
possible to communicate via the traction conductors. It is probably 
worth the effort to do so because it would allow you to incorporate the 
BMS in the cell. Sealing the BMS inside each cell could be very useful, 
especially from a warranty/liability angle. The cell manufacturer would 
love to have a log of the SOC history of the cell.

Communicating _to_ the BMS is simple. You have two VERY large 
transmitters, the charger and the inverter. Simply frequency modulate 
the pwm of the inverter and/or the charger and put an FM detector in 
each BMS on the cell level. You turn the "noise" source into the 
communication transmitter. Done.

Communication _from_ the cells is not quite as simple, but doable. Use 
the by-pass circuit to talk to the outside world. Put a capacitor in 
parallel with the by-pass resistor so that when you switch on the 
resistor, you get a spike. Again, you can transmit via FM using "spikes" 
generated by switching the by-pass on and off briefly.

There are a few clever tricks you can employ. During charging, you can 
have the charger pause for a regular "moment of silence" in which the 
BMS can communicate quickly and in the clear without having to "shout" 
over the charger PWM. Perhaps the same thing could occur to a lesser 
extent with the inverter.

Also, cells that are in a high SOC or low SOC have a high impedance, 
which would tend to make the BMS signal "louder". Since this is the most 
critical time for BMS communication, this helps quite a bit. During 
these times they can "scream" to the inverter to stop for a moment so 
they can give details about the problem.

Just a thought

     Bill D.

On 4/29/2020 9:35 AM, Lawrence Winiarski via EV wrote:
>> Because there are no "mains" in a vehicle.???
> Is it really "That" Noisy?   I suspect it is very doable, it's just that no 
> one has done it yet.The trick is probably using signal processing to get rid 
> of the noise and doing extremelylow bit rates, which is fine for a BMS.    
> Ham radio guys can send stuff over the entire earthon 10 watts using 
> techniques like jt65.   I expect they can deal with a little noise.   it's 
> justnot going to be trivial, but it would be doable.
>
> IMHO the main use for the BMS is in charging anyway.
>
>    On Tuesday, April 28, 2020, 2:12:26 PM PDT, Lee Hart 
> wrote:
>  
>  Lawrence Winiarski wrote:
>> Anyone know anything about data over powerlines?  Why can't the BMS
>> communicate over the mains?
> Because there are no "mains" in a vehicle.
>
> That said, it is possible to communicate via the DC power cables already
> connected to each cell. But this is an extremely noisy environment. It
> would require substantial filtering and protection to keep driving
> currents from trashing data transfers. Some chargers are also extremely
> noisy, and could block data transfers while charging.
>
> Lee


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Re: [EVDL] Minibms?

[Peter C. Thompson via EV]

PLC is one of my least preferred communications transports. Maybe 
because it's a huge percentage of failures when charging, maybe because 
there aren't that many vendors (for EVSE, it is dominated by a very 
large chipmaker in San Diego).


Since this is going to be in an EV, I would prefer to use 100BaseT1, as 
that is the current design win for EVs.  Yeah, totally overkill as far 
as bandwidth goes, but almost totally immune to noise - even without 
shielding.  CAN BUS requires some shielding, and has other limits.


BMS is used during three phases:  charging, discharging, and storage 
(keeping track of SoC, temperature, resistance). When the environment is 
really noisy (think full power), you will REALLY need to make sure you 
aren't draining your batteries too much.


Cheers, Peter

On 4/28/20 2:35 PM, Lawrence Winiarski via EV wrote:

Because there are no "mains" in a vehicle.???

Is it really "That" Noisy?   I suspect it is very doable, it's just that no one 
has done it yet.The trick is probably using signal processing to get rid of the noise and 
doing extremelylow bit rates, which is fine for a BMS.    Ham radio guys can send stuff 
over the entire earthon 10 watts using techniques like jt65.   I expect they can deal 
with a little noise.   it's justnot going to be trivial, but it would be doable.

IMHO the main use for the BMS is in charging anyway.

On Tuesday, April 28, 2020, 2:12:26 PM PDT, Lee Hart 
 wrote:
  
  Lawrence Winiarski wrote:

Anyone know anything about data over powerlines?  Why can't the BMS
communicate over the mains?

Because there are no "mains" in a vehicle.

That said, it is possible to communicate via the DC power cables already
connected to each cell. But this is an extremely noisy environment. It
would require substantial filtering and protection to keep driving
currents from trashing data transfers. Some chargers are also extremely
noisy, and could block data transfers while charging.

Lee


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[EVDL] Communicating over "mains" (Was: Minibms?)

[Bill Dube via EV]

I have thought about doing this for perhaps 20 years. It may well be 
possible to communicate via the traction conductors. It is probably 
worth the effort to do so because it would allow you to incorporate the 
BMS in the cell. Sealing the BMS inside each cell could be very useful, 
especially from a warranty/liability angle. The cell manufacturer would 
love to have a log of the SOC history of the cell.


Communicating _to_ the BMS is simple. You have two VERY large 
transmitters, the charger and the inverter. Simply frequency modulate 
the pwm of the inverter and/or the charger and put an FM detector in 
each BMS on the cell level. You turn the "noise" source into the 
communication transmitter. Done.


Communication _from_ the cells is not quite as simple, but doable. Use 
the by-pass circuit to talk to the outside world. Put a capacitor in 
parallel with the by-pass resistor so that when you switch on the 
resistor, you get a spike. Again, you can transmit via FM using "spikes" 
generated by switching the by-pass on and off briefly.


There are a few clever tricks you can employ. During charging, you can 
have the charger pause for a regular "moment of silence" in which the 
BMS can communicate quickly and in the clear without having to "shout" 
over the charger PWM. Perhaps the same thing could occur to a lesser 
extent with the inverter.


Also, cells that are in a high SOC or low SOC have a high impedance, 
which would tend to make the BMS signal "louder". Since this is the most 
critical time for BMS communication, this helps quite a bit. During 
these times they can "scream" to the inverter to stop for a moment so 
they can give details about the problem.


Just a thought

    Bill D.

On 4/29/2020 9:35 AM, Lawrence Winiarski via EV wrote:

Because there are no "mains" in a vehicle.???

Is it really "That" Noisy?   I suspect it is very doable, it's just that no one 
has done it yet.The trick is probably using signal processing to get rid of the noise and 
doing extremelylow bit rates, which is fine for a BMS.    Ham radio guys can send stuff 
over the entire earthon 10 watts using techniques like jt65.   I expect they can deal 
with a little noise.   it's justnot going to be trivial, but it would be doable.

IMHO the main use for the BMS is in charging anyway.

On Tuesday, April 28, 2020, 2:12:26 PM PDT, Lee Hart 
 wrote:
  
  Lawrence Winiarski wrote:

Anyone know anything about data over powerlines?  Why can't the BMS
communicate over the mains?

Because there are no "mains" in a vehicle.

That said, it is possible to communicate via the DC power cables already
connected to each cell. But this is an extremely noisy environment. It
would require substantial filtering and protection to keep driving
currents from trashing data transfers. Some chargers are also extremely
noisy, and could block data transfers while charging.

Lee



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[EVDL] Lincoln cancels using rivian> (fmc pulls a fakey, ?pr-hoopla?)

[evln via EV]

https://www.autoblog.com/2020/04/28/lincoln-rivian-platform-canceled/
Lincoln cancels plan to build electric vehicle on Rivian's platforme
Apr 28th 2020  Lincoln says it will build its own EV in the future ...
Lincoln has canceled its plan to use the Rivian skateboard platform to
underpin a new electric vehicle in 2022 ... Lincoln hasn’t specified any
product details or timing for when this mystery electric vehicle will launch
... (uses pandemic as excuse)
https://cdn.vox-cdn.com/uploads/chorus_image/image/66722186/akrales_190418_3382_0149.0.jpg


https://www.collinsdictionary.com/us/dictionary/english/fakey
 fakey
...
https://www.google.com/search?q=lincoln+rivian
 search on  lincoln rivian
https://www.google.com/search?q=lincoln+rivian+canceled


+ (EV related - EV-leasees BEWARE!)
https://autos.yahoo.com/dealers-aren-t-letting-customers-18062.html
Some Dealers Aren’t Letting Customers Return Leased Vehicles
April 27, 2020 [Car and Driver] ... A USA Today report told the stories of
several customers with expiring leases who had trouble returning the
vehicles to dealerships during this time of coronavirus pandemic. Some
dealers wouldn't take the vehicles unless customers leased a new one, while
others simply said that they didn't have room for any other vehicles ...




For EVLN EV-newswire posts view:
 http://www.evdl.org/archive/
https://mail-archive.com/ev@lists.evdl.org/maillist.html


{brucedp.neocities.org}

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Re: [EVDL] Minibms?

[Robert Bruninga via EV]

Why not optoisolators.  Much easier than having to make dozens of optical
fiber connections.
Bob

-Original Message-
From: EV  On Behalf Of Mr. Sharkey via EV
Sent: Tuesday, April 28, 2020 3:44 PM
To: ev@lists.evdl.org
Cc: Mr. Sharkey 
Subject: Re: [EVDL] Minibms?

My fantasy BMS would be to have the cell modules communicate with the
downstream electronics by way of fiber optic cable. Think of it, no
galvanic coupling, complete lack of magnetic induction pickup (no
shielding needed), wideband data path, low/no RF generation. A very simple
system could be a loop-through with repeaters at each module for data from
individual cells (would need each module to transmit it's address), while
a more full-featured version would use a star/hub configuration (simpler,
but larger tangle of cables). We just need a home splicing/termination kit
and it's time to rock...

 > Only complaint I would make is that it uses wireless communication -  >
using CAN BUS or 100BaseT1 would be better

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Re: [EVDL] Minibms?

[Lawrence Winiarski via EV]

> Because there are no "mains" in a vehicle.???

Is it really "That" Noisy?   I suspect it is very doable, it's just that no one 
has done it yet.The trick is probably using signal processing to get rid of the 
noise and doing extremelylow bit rates, which is fine for a BMS.    Ham radio 
guys can send stuff over the entire earthon 10 watts using techniques like 
jt65.   I expect they can deal with a little noise.   it's justnot going to be 
trivial, but it would be doable.    

IMHO the main use for the BMS is in charging anyway.   

   On Tuesday, April 28, 2020, 2:12:26 PM PDT, Lee Hart 
 wrote:  
 
 Lawrence Winiarski wrote:
> Anyone know anything about data over powerlines?  Why can't the BMS
> communicate over the mains?

Because there are no "mains" in a vehicle.

That said, it is possible to communicate via the DC power cables already 
connected to each cell. But this is an extremely noisy environment. It 
would require substantial filtering and protection to keep driving 
currents from trashing data transfers. Some chargers are also extremely 
noisy, and could block data transfers while charging.

Lee
-- 
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    - something to do
    - something to look forward to
    - someone to love
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Re: [EVDL] Minibms?

[Lawrence Winiarski via EV]

Anyone know anything about data over powerlines?   Why can't the BMS 
communicate over the mains?   
 

On Tuesday, April 28, 2020, 1:55:18 PM PDT, Lee Hart via EV 
 wrote:  
 
 Mr. Sharkey via EV wrote:
> My fantasy BMS would be to have the cell modules communicate with the
> downstream electronics by way of fiber optic cable. Think of it, no
> galvanic coupling, complete lack of magnetic induction pickup (no
> shielding needed), wideband data path, low/no RF generation.

I've done a simple version of this. *Very* simple! :-)

My zener-lamp regulators are nothing but a zener diode and tungsten 
light bulb. They are chosen not to conduct until the battery voltage 
goes above the "fully charged" voltage. Then the zener conducts, and the 
lamp lights to load down the charger and provide a visual indication.

But there is no light in a battery box. A light sensor anywhere in the 
box won't see light until some regulator starts to conduct. So, I used a 
cheap "night light" as my sensor. It is on when the box is dark, holding 
a relay on to enable the charger. It turns off when it sees light; the 
relay drops, and the charger switches to off or float.

Now, this is probably *too* simple for an expensive lithium pack. I used 
it on lead-acids, which are a lot more forgiving. But it does make the 
point that KISS designs can be a heck of a lot simpler and cheaper than 
the usual high-tech massive-overkill solutions.

Lee Hart

-- 
If happiness is on your mind, here's a daily list to find:
    - something to do
    - something to look forward to
    - someone to love
    - someone to take good care of
    - and misbehave, just a little
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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Re: [EVDL] Minibms?

[Lee Hart via EV]

Mr. Sharkey via EV wrote:

My fantasy BMS would be to have the cell modules communicate with the
downstream electronics by way of fiber optic cable. Think of it, no
galvanic coupling, complete lack of magnetic induction pickup (no
shielding needed), wideband data path, low/no RF generation.


I've done a simple version of this. *Very* simple! :-)

My zener-lamp regulators are nothing but a zener diode and tungsten 
light bulb. They are chosen not to conduct until the battery voltage 
goes above the "fully charged" voltage. Then the zener conducts, and the 
lamp lights to load down the charger and provide a visual indication.


But there is no light in a battery box. A light sensor anywhere in the 
box won't see light until some regulator starts to conduct. So, I used a 
cheap "night light" as my sensor. It is on when the box is dark, holding 
a relay on to enable the charger. It turns off when it sees light; the 
relay drops, and the charger switches to off or float.


Now, this is probably *too* simple for an expensive lithium pack. I used 
it on lead-acids, which are a lot more forgiving. But it does make the 
point that KISS designs can be a heck of a lot simpler and cheaper than 
the usual high-tech massive-overkill solutions.


Lee Hart

--
If happiness is on your mind, here's a daily list to find:
- something to do
- something to look forward to
- someone to love
- someone to take good care of
- and misbehave, just a little
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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Re: [EVDL] EV Digest, Vol 90, Issue 34

[Offgrid Systems via EV]

On 4/28/2020 10:25 AM, ev-requ...@lists.evdl.org wrote:

"https://github.com/offgridsystems (github resource repository)

Tim Economu's qualifications and background are impeccable, you couldn't ask 
for a better collaborator on a project like this.

"


Hello all,

Just wanted to respond to a couple of comments in the last archive, and 
maybe introduce myself. I've been an "active listener" on EVDL for 
years, and now its nice to be able to give a little back to the active 
EV community, so I'm coming out of the woodwork so to speak. If I might 
introduce myself, I spent most of the last 30 years designing power 
inverters and battery chargers (and being partial owner), of companies 
such as Trace Engineering, Xantrex, Magnum, and a slew of smaller 
companies doing solar, battery, and renewable energy projects in the 
great Pacific Northwest. You might even have one of my inverters in your 
RV, boat or house, whether you are offgrid or grid-tied, whether it's 
sinewave or not. I've done some conversions, and some work on OEM EV's, 
designed my own ground-up custom electric bikes and motorcycles, and am 
currently converting all my fossil stuff to battery electric, including 
my old Dodge camper van. So far I am about 95% renewable, the last 5% is 
mainly my diesel tractor...which I actually have a motor and controller 
procured for. I've also done the electrical design for a number of solar 
projects, including the 75kw community solar farm at Greenbank Farm on 
Whidbey.


It was natural to pick a battery project, since I started out working on 
lead batteries many years ago, transitioned to doing nickel chemistries, 
then fool cells, and then finally the last 10 year doing lithium cell 
based packs. I noticed after Tesla started that not many folks was 
taking the patents and doing something more universally germaine, such 
as powerwall, bicycle, auto, and marine applications. And thinking that 
with computer and EV boom (which I still see coming) there will be a LOT 
of used and new 18650 and 2170 cylindrical cells out there in the world. 
Also after a few years (and getting generous payoffs from those 
aforementioned companies) I decided to open source my project, and give 
away the intellectual property, so others can use what they need from it.


To specifically answer some of the questions posted, I'll offer these 
comments:


The DKblock is designed for either repurposing used, or new 18650 cells, 
and being able to change out the cells easily when worn or failed, and 
keep all the rest of the system in place. It was designed to be wireless 
for the communications between the blocks and the Pack Supervisor board 
to keep the small wire pack wiring to a minimum, for reliability 
improvement, and to allow subpacks to be in different locations. I won't 
go on and on since you can go look at it yourself because it's open source.


The basic DKblock has 20 cells in a 2S10P configuration. You can use my 
plastic parts on ebay (search DKblock) or print your own. Same with the 
boards you can make your own, or purchase. Same with the firmware except 
it's free, and you can modify if for your own purpose! Right now the 
system is only good to about 20 blocks in series, or about 60 blocks 
total (3 par strings of 20 blocks each). But I am working on V2 which 
will be much more capable in terms of subpack spacing for longer 
distances, and more blocks allowed, maybe up to 100 blocks in series, 
and a few more features.


The block (Block Manager) does all of the cell management, temperatures, 
volts, etc. The Pack Supervisor does all the pack related stuff, 
voltage, current, temp, over-under voltage, overcurrent and over-under 
temperature control with output relays for control, based on it's own 
sensors, and the data coming in from each separate block.


I hope that answers the basic questions about the DKblock, and the 
origination. I hope that the introduction does not seem too self 
serving, but I know if use something that someone else designed, it is 
nice to know who they are, and where they come from, especially when it 
comes to batteries. And that is probably not just me. And thanks for the 
kind words from Peri and Mr. Sharkey!


Tim Economu, Offgrid Systems LLC, Whidbey Island, renewable power. 
https://dkblock922508958.wordpress.com



On 4/28/2020 10:25 AM, ev-requ...@lists.evdl.org wrote:

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Re: [EVDL] Minibms?

[Mr. Sharkey via EV]

My fantasy BMS would be to have the cell modules communicate with the 
downstream electronics by way of fiber optic cable. Think of it, no 
galvanic coupling, complete lack of magnetic induction pickup (no 
shielding needed), wideband data path, low/no RF generation. A very 
simple system could be a loop-through with repeaters at each module 
for data from individual cells (would need each module to transmit 
it's address), while a more full-featured version would use a 
star/hub configuration (simpler, but larger tangle of cables). We 
just need a home splicing/termination kit and it's time to rock...


> Only complaint I would make is that it uses wireless communication -
> using CAN BUS or 100BaseT1 would be better

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Re: [EVDL] Minibms?

[Peter C. Thompson via EV]

Wow, that is a very impressive open-source project!

Only complaint I would make is that it uses wireless communication - 
using CAN BUS or 100BaseT1 would be better - especially when you are 
putting blocks into different parts of the EV.  For example, in my 914, 
I had 3 separate compartments for my batteries.


Is there interest in taking this design and porting it to large format 
batteries?  That's what I was getting from the discussion of the 
miniBMS, in any case.


I'm definitely interested in helping with this project - I'm really good 
at programming, not so good at electronics.  :)


Cheers, Peter

On 4/28/20 9:28 AM, Peri Hartman via EV wrote:
To follow up a bit, I have had several email exchanges with Tim. He 
has an amazing product which is open source and also available on 
ebay. I'm still working out my requirements. It seems every time I'm 
"done" the next time I look at my calcs I find a problem :) Plus, 
there are many options on what voltage or current to pick, in order to 
keep the price down for various components.


Anyway, I think I'm likely to buy a few of his blocks and BMS boards. 
Not sure about the central board yet, might integrate that with software.


His blocks are configurable so that you can have groups of parallel 
cells within each block (I think this is true) rather than the whole 
block as a series of individual cells.


Peri

-- Original Message --
From: "Mr. Sharkey via EV" 
To: ev@lists.evdl.org
Cc: "Mr. Sharkey" 
Sent: 28-Apr-20 8:21:35 AM
Subject: Re: [EVDL] Minibms?

A couple of weeks back, there was an ongoing discussion about 
building a custom battery that Peri was designing. An offshoot post 
from that by Tim Economu offered an open source BMS/cell module 
assembly project that he had worked up:


http://electric-vehicle-discussion-list.413529.n4.nabble.com/custom-battery-DKblock-td4696973.html 
(pointing to the Nabble archive)


https://github.com/offgridsystems (github resource repository)

I was surprised that this received no replies, as it looked like an 
interesting project. I had a look at the source code for the "Block 
Manager" (cell level monitor), and although it had features that 
wouldn't necessarily apply to a simple management system, all of the 
programming that would be needed was there and well written. It would 
likely be a matter of removing unneeded code for features that 
weren't going to be employed (thermal management for example), as 
well as adjusting voltage setpoints for your particular cell chemistry.


Tim Economu's qualifications and background are impeccable, you 
couldn't ask for a better collaborator on a project like this.


All of the components to replicate a v.2 or v.3 MiniBMS knock-off are 
available in through-the-hole packages. The parts count is low enough 
that they would still be fairly compact when completed.



> Even the v3 boards are not terribly complicated from a circuit
> standpoint.  And I feel confident that the firmware they run could be
> replicated. I could easily see creating an open source PCB and 
firmware

> again.

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Re: [EVDL] Minibms?

[Peri Hartman via EV]

To follow up a bit, I have had several email exchanges with Tim. He has 
an amazing product which is open source and also available on ebay. I'm 
still working out my requirements. It seems every time I'm "done" the 
next time I look at my calcs I find a problem :) Plus, there are many 
options on what voltage or current to pick, in order to keep the price 
down for various components.


Anyway, I think I'm likely to buy a few of his blocks and BMS boards. 
Not sure about the central board yet, might integrate that with 
software.


His blocks are configurable so that you can have groups of parallel 
cells within each block (I think this is true) rather than the whole 
block as a series of individual cells.


Peri

-- Original Message --
From: "Mr. Sharkey via EV" 
To: ev@lists.evdl.org
Cc: "Mr. Sharkey" 
Sent: 28-Apr-20 8:21:35 AM
Subject: Re: [EVDL] Minibms?


A couple of weeks back, there was an ongoing discussion about building a custom 
battery that Peri was designing. An offshoot post from that by Tim Economu 
offered an open source BMS/cell module assembly project that he had worked up:

http://electric-vehicle-discussion-list.413529.n4.nabble.com/custom-battery-DKblock-td4696973.html
 (pointing to the Nabble archive)

https://github.com/offgridsystems (github resource repository)

I was surprised that this received no replies, as it looked like an interesting project. 
I had a look at the source code for the "Block Manager" (cell level monitor), 
and although it had features that wouldn't necessarily apply to a simple management 
system, all of the programming that would be needed was there and well written. It would 
likely be a matter of removing unneeded code for features that weren't going to be 
employed (thermal management for example), as well as adjusting voltage setpoints for 
your particular cell chemistry.

Tim Economu's qualifications and background are impeccable, you couldn't ask 
for a better collaborator on a project like this.

All of the components to replicate a v.2 or v.3 MiniBMS knock-off are available 
in through-the-hole packages. The parts count is low enough that they would 
still be fairly compact when completed.


> Even the v3 boards are not terribly complicated from a circuit
> standpoint.  And I feel confident that the firmware they run could be
> replicated. I could easily see creating an open source PCB and firmware
> again.

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Re: [EVDL] Minibms?

[Mr. Sharkey via EV]

A couple of weeks back, there was an ongoing discussion about 
building a custom battery that Peri was designing. An offshoot post 
from that by Tim Economu offered an open source BMS/cell module 
assembly project that he had worked up:


http://electric-vehicle-discussion-list.413529.n4.nabble.com/custom-battery-DKblock-td4696973.html 
(pointing to the Nabble archive)


https://github.com/offgridsystems (github resource repository)

I was surprised that this received no replies, as it looked like an 
interesting project. I had a look at the source code for the "Block 
Manager" (cell level monitor), and although it had features that 
wouldn't necessarily apply to a simple management system, all of the 
programming that would be needed was there and well written. It would 
likely be a matter of removing unneeded code for features that 
weren't going to be employed (thermal management for example), as 
well as adjusting voltage setpoints for your particular cell chemistry.


Tim Economu's qualifications and background are impeccable, you 
couldn't ask for a better collaborator on a project like this.


All of the components to replicate a v.2 or v.3 MiniBMS knock-off are 
available in through-the-hole packages. The parts count is low enough 
that they would still be fairly compact when completed.



> Even the v3 boards are not terribly complicated from a circuit
> standpoint.  And I feel confident that the firmware they run could be
> replicated. I could easily see creating an open source PCB and firmware
> again.

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Re: [EVDL] Stranded ICE assets

[Jim Walls via EV]

On 04/26/2020 19:55, Lee Hart via EV wrote:
Yes, if you live in a big city (especially in California), seeing EVs 
is a daily occurrence. CA is reporting something like 15 EVs per 1000 
people.


Daily?  Here in the Los Angeles suburbs, I can't go more than a minute 
or two on the freeway without seeing an EV.  They're everywhere...



--
73
-
Jim Walls - K6CCC
j...@k6ccc.org
Ofc:  818-548-4804
http://members.dslextreme.com/users/k6ccc/
AMSAT Member 32537 - WSWSS Member 395

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Re: [EVDL] Minibms?

[Neal, Gary via EV]

Per Jay's comment "Other BMS's with cell level monitoring/reporting offer a 
better option and their price points are coming down", does anyone have 
up-to-date research or have recent first-hand experience with 
commercially-available BMS for the DIY'er?  Our technical requirements are:

1. Cell-level voltage monitoring/balancing
2. Capable of up to ~400 V pack voltage (~100 series cells)
3. Temperature monitoring (doesn't have to be cell-level, but "module" level 
would be good)
4. CAN communication to a supervisory controller
5. Nice to have (although maybe rare?)
a. Control precharge contactors
b. Control main contactors
c. Ground fault monitoring

Because we have enough other risks in our student team's custom EV conversions, 
we're looking for a commercially-available BMS product that hopefully minimizes 
the Energy Storage System risks without inherent "student build" BMS issues 
biting us too.

Plus, all the other "wants": reliable, inexpensive, easily purchasable, gets me 
a drink when I'm thirsty, etc.

Thanks,
Gary

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Re: [EVDL] Minibms?

[Mark Grasser via EV]

Jay,
I know it is cumbersome but we are still running our wave solder machine, 
making our own through hole product. We could do small runs easily, that’s what 
we do anyway. You'd have to come back to through hole though.
Mark

-Original Message-
From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of Jay Summet via EV
Sent: Tuesday, April 28, 2020 7:31 AM
To: ev@lists.evdl.org
Cc: Jay Summet
Subject: Re: [EVDL] Minibms?

Even the v3 boards are not terribly complicated from a circuit 
standpoint.  And I feel confident that the firmware they run could be 
replicated. I could easily see creating an open source PCB and firmware 
again.  The difficulty is with manufacture/distribution in my mind.  
There are a few assembly houses that will do short runs, but it's very 
hard to do that economically.  So somebody could build/sell replacement 
units, but I fear that the market is relatively small.   (mostly limited 
to replacements for existing installations)


Other BMS's with cell level monitoring/reporting offer a better option 
and their price points are coming down.

I've been strongly considering a BMS upgrade for my truck as the next 
major upgrade (due to the fact that the miniBMS modules are not easily 
available for replacement, and do a poor job of keeping the pack balanced.)

Jay

On 4/27/20 7:26 PM, Mr. Sharkey via EV wrote:
> The MiniBMS system was originally started as an open source project by 
> users of the DIY Electric Car forum. It was mostly spearheaded by 
> Dimitri, with input from several interested users. The first version 
> as intended to be able to used with all the cell modules on one PCB, 
> with voltage sense wiring going to each cell. It could also be cut 
> into individual PCBs and cell-mounted. There are vestigial PCB traces 
> for the opto interconnection even on the v.2 cell modules from this 
> design (I cut those traces off individual boards, as they add to the 
> creepage problem). A 4x4/16 cell PCB was standard, but other 
> configurations were possible.
>
> After the basic system was designed by the group, and Dimitri had a 
> few runs of v.1 and then v.2 boards printed and stuffed, he decided 
> that the project was no longer open source, and took it private, much 
> to the dissatisfaction of the other participants. It wasn't a lot 
> after that the he sold the intellectual property rights and name to 
> EVPower, who further refined the design and packaging.
>
> I agree that we have a chance to reintroduce a good portion of these 
> available cell modules to the EV community for those who are 
> interested. How shall we procede?
>
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Re: [EVDL] Minibms?

[Jay Summet via EV]

Even the v3 boards are not terribly complicated from a circuit 
standpoint.  And I feel confident that the firmware they run could be 
replicated. I could easily see creating an open source PCB and firmware 
again.  The difficulty is with manufacture/distribution in my mind.  
There are a few assembly houses that will do short runs, but it's very 
hard to do that economically.  So somebody could build/sell replacement 
units, but I fear that the market is relatively small.   (mostly limited 
to replacements for existing installations)



Other BMS's with cell level monitoring/reporting offer a better option 
and their price points are coming down.


I've been strongly considering a BMS upgrade for my truck as the next 
major upgrade (due to the fact that the miniBMS modules are not easily 
available for replacement, and do a poor job of keeping the pack balanced.)


Jay

On 4/27/20 7:26 PM, Mr. Sharkey via EV wrote:
The MiniBMS system was originally started as an open source project by 
users of the DIY Electric Car forum. It was mostly spearheaded by 
Dimitri, with input from several interested users. The first version 
as intended to be able to used with all the cell modules on one PCB, 
with voltage sense wiring going to each cell. It could also be cut 
into individual PCBs and cell-mounted. There are vestigial PCB traces 
for the opto interconnection even on the v.2 cell modules from this 
design (I cut those traces off individual boards, as they add to the 
creepage problem). A 4x4/16 cell PCB was standard, but other 
configurations were possible.


After the basic system was designed by the group, and Dimitri had a 
few runs of v.1 and then v.2 boards printed and stuffed, he decided 
that the project was no longer open source, and took it private, much 
to the dissatisfaction of the other participants. It wasn't a lot 
after that the he sold the intellectual property rights and name to 
EVPower, who further refined the design and packaging.


I agree that we have a chance to reintroduce a good portion of these 
available cell modules to the EV community for those who are 
interested. How shall we procede?


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