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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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
-- 
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?

[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] 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] 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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Re: [EVDL] Minibms?

[Lawrence Winiarski via EV]

I think I understand the history.    I need to have a few for myself,  (I'd 
like around 20) but beyond that 
It seems ultimately we should make a PCB gerber file and opensource it for v2?  
Seems a reasonable start.    

Mr Sharkey:   Are you in Oregon?   I live in Monroe Oregon.

On Monday, April 27, 2020, 4:35:27 PM PDT, 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?

[Mr. Sharkey via EV]

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?

[Willie via EV]

On 4/27/20 3:13 PM, Mr. Sharkey via EV wrote:
I sense a beautiful online relationship in the making here. 
Unfortunately, I'm using the Nabble web archive to read messages, which 
means I can't see your contact information (or even your name, since 
Nabble bollixed up the interface a few years ago).


Here's a little email address puzzle to confound the spambots, I'm sure 
that ordinary humans are clever enough to figure it out:


Mary
Romeo


I knew MrSharkey's address and thought I was making a private reply. 
However...


This should go to MrSharkey via Bcc:  Along with my address.

I was buying the EVPower modules long before the miniBMS modules were 
offered.  So, to the the best of my knowledge, EVPower long preceded 
miniBMS.  I felt a little guilt about switching to miniBMS but it was 
hard to get what was needed from EVPower.  In retrospect, a mistake. 
The miniBMS have proven to be very troublesome.  At least when exposed 
to the conditions my batteries were exposed to.


My current guesstimate is around 150 miniBMS and maybe up to 50 EVPower. 
 I think a large fraction of each work.  The miniBMS are a mixture of 
old (which will eventually completely drain a cell) and newer ones (with 
blinking lights that are supposed to tell you which have gone out of 
bounds and are supposed to quit drawing current at around 2v).

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Re: [EVDL] Minibms?

[Lawrence Winiarski via EV]

Hi Willie.   I think we are serious about those boards.   

How do we pay you?   Are they still in working order?   

 

On Monday, April 27, 2020, 12:52:49 PM PDT, Willie via EV 
 wrote:  
 
 

On 4/27/20 2:25 PM, Mr. Sharkey via EV wrote:

> I'd be glad to relate any info that helps you get these working, or if 
> you decide not to repair them, I'd be interesting in purchasing the dead 
> ones as possible spares for my EV. I have schematics for the cell and 
> head boards, etc.

Send me your shipping address and I will send you a bunch.  Maybe around 
200.  You may then decide if they are worth anything.

Do you want any Australian "EVPower" cell modules?  They were MUCH more 
reliable but apparently no longer available.  Nicely potted up. They 
have flat copper cell connections rather than "fly wires".

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Re: [EVDL] Minibms?

[Lawrence Winiarski via EV]

I'd love to get some.   I have a use for 20 cell boards and perhaps a head 
board.lawrence_winiarski    at  yankee alpha hotel oscar oscar dot charlie 
oscar mike


On Monday, April 27, 2020, 1:16:51 PM PDT, Mr. Sharkey via EV 
 wrote:  
 
 I sense a beautiful online relationship in the making here. 
Unfortunately, I'm using the Nabble web archive to read messages, 
which means I can't see your contact information (or even your name, 
since Nabble bollixed up the interface a few years ago).

Here's a little email address puzzle to confound the spambots, I'm 
sure that ordinary humans are clever enough to figure it out:

Mary
Romeo
Seirra
Hotel
Alpha
Romeo
Kilo
Echo
Yankee
@ (at)
Juliet
Uniform
November
Oscar
. (dot)
Charlie
Oscar
Mary

If these boards hold any promise for continued use, perhaps repairing 
them would make a good social distancing cottage industry for the 
duration of the pandemic. Distributing the operational boards back to 
the EV community for a modest cost would be my only payback aside 
from the security of having some spares on hand (I lose a cell board 
once or twice a year, and having something on the shelf to bolt-on 
instead of inheriting an instant repair project would be mighty nice).

The Australian modules were the result of Dimitri selling off his 
business "Clean Power Auto" and all the IP to the MiniBMS product. 
The new owners recognized some of the shortcomings, and made 
corrections, the most significant of which was potting the cell 
modules in epoxy to eliminate the voltage creep and corrosion 
problems. Repairable? No idea, would need to hack into a few and see 
what's left over.

Oh, and to the original poster, I can direct you to a schematic of my 
simple test jig, which can help diagnose and proof cell modules, very 
helpful if you have even a couple to check out.

 > Send me your shipping address and I will send you a bunch.  Maybe around
 > 200.  You may then decide if they are worth anything.

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Re: [EVDL] Minibms?

[Mr. Sharkey via EV]

I sense a beautiful online relationship in the making here. 
Unfortunately, I'm using the Nabble web archive to read messages, 
which means I can't see your contact information (or even your name, 
since Nabble bollixed up the interface a few years ago).


Here's a little email address puzzle to confound the spambots, I'm 
sure that ordinary humans are clever enough to figure it out:


Mary
Romeo
Seirra
Hotel
Alpha
Romeo
Kilo
Echo
Yankee
@ (at)
Juliet
Uniform
November
Oscar
. (dot)
Charlie
Oscar
Mary

If these boards hold any promise for continued use, perhaps repairing 
them would make a good social distancing cottage industry for the 
duration of the pandemic. Distributing the operational boards back to 
the EV community for a modest cost would be my only payback aside 
from the security of having some spares on hand (I lose a cell board 
once or twice a year, and having something on the shelf to bolt-on 
instead of inheriting an instant repair project would be mighty nice).


The Australian modules were the result of Dimitri selling off his 
business "Clean Power Auto" and all the IP to the MiniBMS product. 
The new owners recognized some of the shortcomings, and made 
corrections, the most significant of which was potting the cell 
modules in epoxy to eliminate the voltage creep and corrosion 
problems. Repairable? No idea, would need to hack into a few and see 
what's left over.


Oh, and to the original poster, I can direct you to a schematic of my 
simple test jig, which can help diagnose and proof cell modules, very 
helpful if you have even a couple to check out.


> Send me your shipping address and I will send you a bunch.  Maybe around
> 200.  You may then decide if they are worth anything.

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Re: [EVDL] Minibms?

[Willie via EV]

On 4/27/20 2:25 PM, Mr. Sharkey via EV wrote:

I'd be glad to relate any info that helps you get these working, or if 
you decide not to repair them, I'd be interesting in purchasing the dead 
ones as possible spares for my EV. I have schematics for the cell and 
head boards, etc.


Send me your shipping address and I will send you a bunch.  Maybe around 
200.  You may then decide if they are worth anything.


Do you want any Australian "EVPower" cell modules?  They were MUCH more 
reliable but apparently no longer available.  Nicely potted up. They 
have flat copper cell connections rather than "fly wires".


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Re: [EVDL] Minibms?

[Lawrence Winiarski via EV]

Funny.    That's exactly what went wrong.    I have a few optorelays in my ebay 
cart as we speak.
Yes, I'll repair,  extend the same offer to you if you get decide to get rid of 
yours. :-)
I've got the old schematic for v.2 which seems to be about right.   Don't know 
anything about v3 or what the differences are.
I've never done anything with surface mount, but I thought perhaps this might 
be a good project to do something useful and learn on.


On Monday, April 27, 2020, 12:26:37 PM PDT, Mr. Sharkey via EV 
 wrote:  
 
 Depending on the version (and condition) of the boards, they are 
repairable. The most common failure is of the optical relay that 
isolates the cell module from the controller head. It's not a 
particularly expensive part, and although it's surface mount (SMD), 
it has only four leads, and can be replaced using common soldering tools.

I had to rebuild nine of the v.2 Mini BMS boards that I purchased 
with the used Thundersky cells that are in my car now. There were a 
variety of failures, many of which were caused by corrosion and 
creepage between the cell/pack potential and automotive 12 volt 
battery connections. Some through cleaning, PCB trace repairs and 
half a dozen of the optical relays all is operational again. I built 
a test jig to proof each board and gather LVD, HVD, balancing voltage 
and current, etc.

I'd be glad to relate any info that helps you get these working, or 
if you decide not to repair them, I'd be interesting in purchasing 
the dead ones as possible spares for my EV. I have schematics for the 
cell and head boards, etc.

Version 3 boards use an ATTiny microprocessor (AVR), and might be 
repairable, but if the processor needs replacement, that's going to 
be a sticking point without the source code for the chipset.



 > Hi.  I had a few minibms boards quit working and I was wondering if
 > anyone had made a dropin alternative or had some that they might
 > want to sell.

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Re: [EVDL] Minibms?

[Mr. Sharkey via EV]

Depending on the version (and condition) of the boards, they are 
repairable. The most common failure is of the optical relay that 
isolates the cell module from the controller head. It's not a 
particularly expensive part, and although it's surface mount (SMD), 
it has only four leads, and can be replaced using common soldering tools.


I had to rebuild nine of the v.2 Mini BMS boards that I purchased 
with the used Thundersky cells that are in my car now. There were a 
variety of failures, many of which were caused by corrosion and 
creepage between the cell/pack potential and automotive 12 volt 
battery connections. Some through cleaning, PCB trace repairs and 
half a dozen of the optical relays all is operational again. I built 
a test jig to proof each board and gather LVD, HVD, balancing voltage 
and current, etc.


I'd be glad to relate any info that helps you get these working, or 
if you decide not to repair them, I'd be interesting in purchasing 
the dead ones as possible spares for my EV. I have schematics for the 
cell and head boards, etc.


Version 3 boards use an ATTiny microprocessor (AVR), and might be 
repairable, but if the processor needs replacement, that's going to 
be a sticking point without the source code for the chipset.




> Hi.   I had a few minibms boards quit working and I was wondering if
> anyone had made a dropin alternative or had some that they might
> want to sell.

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[EVDL] Minibms?

[Lawrence Winiarski via EV]

Hi.   I had a few minibms boards quit working and I was wondering if anyone had 
made a dropin alternative or had some that they might want to sell.


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Re: [EVDL] MiniBMS replacement boards?

[Mr. Sharkey via EV]

>> A URL or name for this company would be appreciated.

Try this, although it seems some of the products are discontinued/out-of-stock:

https://evparts.com.au/ev-power-bms.html

>> Let me know once you have a few extra to sell.

This will likely be a fall/winter project, once the year's firewood 
is put up and the outdoor chores cease due to the weather.


Another part of the repower project is going to be to rework a Todd 
Power Source to be a lithium-compatible 36v charger. I'll probably 
run barefoot without a BMS in the short term and carefully balance 
and charge manually until I get something worked out.


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Re: [EVDL] MiniBMS replacement boards?

[Willie via EV]

On 13/08/19 17:30, Mr. Sharkey via EV wrote:
Can't say about the availability of v.3 boards, the whole Clean Power 
Auto inventory and business was sold to an Australian or New Zealand 
company that modified the design, but seem to still be supplying units.


The "original" MiniBMS design ~was~ an open source project that was 
developed on the diyelectriccar forums, and went through a couple of 
evolutions as the users there refined the design. Once it was a 
workable, marketable product, Dimitri took it commercial/private and 
basically stiffed the fellow developers, most of whom weren't at all 
happy about that turn of developments.


V.3 boards chucked the four-section LM239/339 comparitor design and 
went to an Atmel ATTiny45v AVR. Obviously, the code is proprietary, 
but really isn't anything a competent Arduino experimenter couldn't 
replicate.


I'm actually developing a similar BMS based on the v.3 boards, but 
with some significant improvements. These will go on the leaf modules 
I just purchased to repower my ElecTrak tractor. I was going to build 
five units that could monitor 5 modules (total of 10 cells), but the 
PC board layout and code would be up for grabs for other users who 
wanted to build their own. Of course, none of it would be based 
directly on the MiniBMS designs, which I consider to be open source by 
default of the cooperation that went into their development from the 
beginning.


If it's helpful, I have circuit schematics for the "v.2" miniBMS 
modules and the head unit, in case anyone needs to do repairs or 
modifications to them. I've repaired and tested quite a few of these, 
the biggest problem seems to be creepage between the pack potential 
and the alarm loop, and defective solid state relays, which are cheap 
and easy to replace.


I was an early customer of an Australian company that did cell modules 
for LFP cells; they had flat copper foils that needed to come close to 
matching cell terminal spacing.  miniBMS came later and seemed to be a 
knockoff but used more versatile "fly wires" .  I have a box full of 
miniBMS modules of various vintages as well as some Australian ones.  I 
can be dealt with.


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Re: [EVDL] MiniBMS replacement boards?

[Jay Summet via EV]

On 8/13/19 6:30 PM, Mr. Sharkey via EV wrote:
> Can't say about the availability of v.3 boards, the whole Clean Power
> Auto inventory and business was sold to an Australian or New Zealand
> company that modified the design, but seem to still be supplying units.

A URL or name for this company would be appreciated.

> 
> I'm actually developing a similar BMS based on the v.3 boards, but with
> some significant improvements. These will go on the leaf modules I just
> purchased to repower my ElecTrak tractor. I was going to build five
> units that could monitor 5 modules (total of 10 cells), but the PC board
> layout and code would be up for grabs for other users who wanted to
> build their own. Of course, none of it would be based directly on the
> MiniBMS designs, which I consider to be open source by default of the
> cooperation that went into their development from the beginning.
> 

Let me know once you have a few extra to sell.
Thanks,
Jay
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Re: [EVDL] MiniBMS replacement boards?

[Mr. Sharkey via EV]

Can't say about the availability of v.3 boards, the whole Clean Power 
Auto inventory and business was sold to an Australian or New Zealand 
company that modified the design, but seem to still be supplying units.


The "original" MiniBMS design ~was~ an open source project that was 
developed on the diyelectriccar forums, and went through a couple of 
evolutions as the users there refined the design. Once it was a 
workable, marketable product, Dimitri took it commercial/private and 
basically stiffed the fellow developers, most of whom weren't at all 
happy about that turn of developments.


V.3 boards chucked the four-section LM239/339 comparitor design and 
went to an Atmel ATTiny45v AVR. Obviously, the code is proprietary, 
but really isn't anything a competent Arduino experimenter couldn't replicate.


I'm actually developing a similar BMS based on the v.3 boards, but 
with some significant improvements. These will go on the leaf modules 
I just purchased to repower my ElecTrak tractor. I was going to build 
five units that could monitor 5 modules (total of 10 cells), but the 
PC board layout and code would be up for grabs for other users who 
wanted to build their own. Of course, none of it would be based 
directly on the MiniBMS designs, which I consider to be open source 
by default of the cooperation that went into their development from 
the beginning.


If it's helpful, I have circuit schematics for the "v.2" miniBMS 
modules and the head unit, in case anyone needs to do repairs or 
modifications to them. I've repaired and tested quite a few of these, 
the biggest problem seems to be creepage between the pack potential 
and the alarm loop, and defective solid state relays, which are cheap 
and easy to replace.


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[EVDL] MiniBMS replacement boards?

[Jay Summet via EV]

I find myself in need of a few spare MiniBMS boards. Specifically, the
small ones programmed for Leaf modules (4.15 volt shunt, 4.20 volt high
alarm/loop drop).

The ones I have say CleanPowerAutoLLC 2014, v3 MiniBMS on the front and
"RZ-01  94V-0CCS  0215" on the back.

I would also consider any "loop style" individual MiniBMS style boards
that I could put into the loop with them, but would prefer the same model.

Anybody have extra stock they are willing to part with or pointers to a
replacement board?   (They look simple enough that I could manufacture
my own if there was an open source design somewhere)

Thanks,
Jay
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[EVDL] MiniBMS & regular intermittent pulsing of loop?

[Jay Summet via EV]

I'm using a miniBMS system in my batteries, and the loop is connected to 
a Thunderstruck motors EVCC unit, which fires off a buzzer if the loop 
drops (indicating a low voltage event) while driving or turns off the 
charger if it's charging (indicating a high voltage event).



A few days ago I was driving around (short trip, pack no where near 
discharged, but not super close to fully charged either...) and the 
buzzer started to sound in a very regular pattern (about 1 second on, 
one second off).


I have never experienced this pattern of sounds before.

Sometimes at the end of a long trip I've gotten a low voltage event and 
the buzzer will sound briefly if I am drawing a lot of amps, but the 
buzzer would always stop as soon as I let up on the throttle.


This buzzing on/off/on/off continued while driving for another mile and 
when I was parked at home. I switched everything off and started it back 
up again (resetting power to the EVCC) and the pulsed buzzing continued.


I have a physical switch in my BMS loop for testing purposes, and when I 
opened it, the buzzer went from intermittent pulsing to solid on, so the 
EVCC was definitely still monitoring the loop.


I have a parallel pack trackr system that monitors the voltage of (every 
pair of) cells and everything looked normal on it, no pair of cells was 
low enough to be triggering a low voltage alarm.


I left the truck sitting for a few hours, and when I tried it again the 
intermittent buzzing had cleared and gone away. I've driven it a good 
100 miles since then with multiple charge cycles and haven't heard it again.



The other option is that the EVCC was signaling the buzzer in it's own 
pattern for some other type of fault (and then honoring the dropped loop 
signal to turn it on continuously), but the support staff at TSM felt 
that the pulsed signal was coming from the BMS loop, and the EVCC manual 
doesn't mention the buzzer sounding for anything other than a BMS loop 
event.


I'm just wondering if anybody has experienced this type of on/off/on/off 
loop signal with the miniBMS boards before, and if so, what it indicates?


Thanks,
Jay



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Re: [EVDL] MiniBMS, was: Bicycle battery

[tomw via EV]

Cor, yes 20% of 4 mA would of course be 0.8 mA...I also wrote the pack
voltage is the same after sitting for two weeks, but I meant to write
Ah...sigh.  When you consider that I usually charge every or every other day
those small drains don't matter since I'm pulling 70 - 120 Ah out over that
time.  That's why I think these things are inconsequential in every day
operation. 

The discussion in this thread has been entertaining, also some good papers
to read.  I agree that there seems to be a difference in theory and practice
due to contaminants and non-ideal manufacturing. Also believing is seeing. 
Yes, I meant to write it that way.  We tend to seek confirming evidence,
accept it readily and uncritically, and scrutinize disconfirming evidence
carefully to find a way to reject it.  That's why two people can read the
same paper and find evidence for their opposing views.  For those interested
see How We Know What Isn't So by Thomas Gilovich.



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[EVDL] MiniBMS, was: Bicycle battery

[Cor van de Water via EV]

Tom,
I am afraid that your calculation has 3 orders of magnitude error:

If nominal drain is 4mA +/-20% then max difference between the drain
from different balancers is in the order of 2mA (milli, not micro),
unless the nominal drain is 4uA (microAmp) then the difference can be less than 
2uA
but that is an unbelievable low power that usually is only possible with a pure 
analog
solution or a very careful designed digital system with extensive power-saving 
modes
and short wake-up times, not a run of the mill digital design. I do not know 
the miniBMS,
so I am assuming that the nominal drain is 4mA which means 0.1Ah per day.

I browsed through the specs of the cell units and I did see a mention of max 
7mA drain
but it was unclear to me if that was the header (central) unit or the per-cell 
unit.

If I want a BMS then I will probably create my own version of MiniBMS per-cell 
unit, because
I do like their approach of a simple daisy chain to indicate a problem 
somewhere, though I may
concentrate several boards together so it is not spread out across the pack, 
but sitting in
a safer location right next to the pack.
I am quite sure that I can get the per-cell drain low enough to not cause much 
imbalance
and make sure that shunting is active on every charge cycle, or I might go for 
Lee Hart's
balancer which makes sure that all cells are at equal voltage, so there is no 
need for 
shunting the excess away.

Cor van de Water
Chief Scientist
Proxim Wireless

office +1 408 383 7626  Skype: cor_van_de_water
XoIP   +31 87 784 1130  private: cvandewater.info
www.proxim.com


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-Original Message-
From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of tomw via EV
Sent: Friday, June 19, 2015 8:05 AM
To: ev@lists.evdl.org
Subject: Re: [EVDL] Bicycle battery

/That is a reason I don't use a cell level BMS. With a cell level BMS like the 
miniBMS there is a constant drain on the cells running the BMS boards and it is 
nearly impossible to make sure that each board uses the _exact_ same current 
regardless of voltage in the cell./

The constant drain is less 4mA with about +/-20% variability, so the difference 
between cells is at most  2 microamp.

/Furthermore, boards like the miniBMS expect that you will balance at the end 
of every charge and last I saw, that balance voltage was at 3.6V or so which is 
over the theoretical 100% SOC level for LiFePO4 cells which leads to potential 
overcharging of the cells on every charge cycle./

Balance voltage on the minibms for LiFePO4 cells has always been 3.5V, from the 
very first ones made to the present. Check the original minibms thread on 
diyelectriccar if you don't believe it.  I purchased some of the first boards 
and am still using them.  Also, 3.6V while charging is not necessarily over the 
theoretical max SoC.  According to Whitacre cell rest voltage of 3.4V is 100% 
SoC.  The voltage will be higher while charging while near full charge due to 
the voltage drop across the cell effective internal resistance. The higher the 
charge current, the higher the cell voltage will be at a given SoC. Of course 
if you go too high in cell voltage (4.2V according to Whitacre) you start to 
break down the electrolyte.  When I charge my pack to 3.53V average cell 
voltage, they are at 3.344V average after  2 hours rest.  CALB and others used 
to spec charge to 4.1 or 4.2V at 0.05C rate, which would result in a full 
charge and rest voltage of about 3.4V per cell.  They haven't spec'ed that for 
years though.  They relaxed it to 3.6V.  I would guess for longer cell life and 
the fact that there is little difference in useable charge.

/If you stop charging without the balancing taking place and/or let the pack 
sit for extended periods of time then the different current draw of each board 
working 24/7 introduces an imbalance in the SOC of the cells in the pack./ 

I do partial charges without any shunting  70% of the time.  When I do charge 
to 3.53V per cell to get shunting, the first cells start shunting about 10 
minutes before charging terminates, and by end of charge all shunt LEDs are on. 
 The highest cells reach about 3.55V.  I've let the car sit for over 2 weeks 
while away for work or on vacation and the pack voltage reads the same voltage 
when I return as when I left.  The next full charge there may be several cells 
that don't shunt, but they all do after a couple of full charges. The pack has 
5 1/2 years and about 45,000 miles on it.

I think you have to keep the scale of things in mind.  These effects are small. 
 I've found them inconsequential in daily operation of the vehicle. 
I think the main effect on cell life is