EV Digest 6769
Topics covered in this issue include:
1) Re: OT: Magnetic fields (Re: magnetic field in EV car?)
by Jeff Shanab <[EMAIL PROTECTED]>
2) Re: magnetic field in EV car?
by Jeff Shanab <[EMAIL PROTECTED]>
3) Re: BMS (Battery Management System (Was: 1-Wire Expertise)
by "(-Phil-)" <[EMAIL PROTECTED]>
4) Re: magnetic field in EV car?
by "(-Phil-)" <[EMAIL PROTECTED]>
5) Re: Sepex regen
by "(-Phil-)" <[EMAIL PROTECTED]>
6) Re: magnetic field in EV car?
by "(-Phil-)" <[EMAIL PROTECTED]>
7) Re: Noodling Lithium prices and batteries
by "Timothy Balcer" <[EMAIL PROTECTED]>
8) Re: How does a 48v motor handle higher voltages?
by "Peter VanDerWal" <[EMAIL PROTECTED]>
9) Re: BMS (Battery Management System (Was: 1-Wire Expertise)
by "Peter VanDerWal" <[EMAIL PROTECTED]>
10) Re: BMS (Battery Management System)
by Steve <[EMAIL PROTECTED]>
11) Re: EMF in EVs (and how to mitigate it)
by "Peter VanDerWal" <[EMAIL PROTECTED]>
12) RE: Vehicle efficiency, wh/mile - cruise control
by "Alan Gideon" <[EMAIL PROTECTED]>
13) Re: magnetic field in EV car?
by "Patrick Robin" <[EMAIL PROTECTED]>
14) RE: Vehicle efficiency, wh/mile - cruise control
by "Peter VanDerWal" <[EMAIL PROTECTED]>
15) Re: Vehicle efficiency, wh/mile
by Rod Dilkes <[EMAIL PROTECTED]>
16) Re: magnetic field in EV car?
by Danny Miller <[EMAIL PROTECTED]>
--- Begin Message ---
Clarification: I know he said relative but for the less newtonian of us...
The field polarity is fixed in a dc series wound motor, the
individual armature winding polarity changes as it crosses under the brush.
I too am not an expert, so I invite criticizim (except "man does your
ascii art suck")
Simple explination?
Power flows in two brushes, say at 0 and 180 degrees(positive) and out
the other 2 brushes, say at 90 and 270 degrees(negative).
All the armature windings are connected in series around the entire armature
As the junction between two windings passes under a brush, it goes from
having a positve brush 90 degrees to it's left and a negative positive
brush to it's immediate right(position 1) to having that Negative brush
to it's immediate left and the other Positive brush 90 degrees to it's
right. (position 2)
Absolute Genius.
Fixed width font
0 90 180 270 360/0
_ _ _ _ _ _ _ _ _ _ _ _
/ \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \...Armature coils
[ ] [ ] [ ] [1] [2] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [...CommBars
|||| |||| |||| ||||
+brush -Brush +brush -brush
-----+--------> - <---------+--------> - <----------- current flow
--- End Message ---
--- Begin Message ---
I just thought of something, If the magnetic field was large, wouldn't
those with hall effect go pedals would have problems?
--- End Message ---
--- Begin Message ---
I have done this kind of IR, (40khz) even outdoors, with as many as 100
nodes this way and no problems. Use a high power IR LED and a modern
monolithic detector with a good optical and electronic discriminator and it
will most definitely work in a battery box, array, or under the hood. As
long as there is something somewhat reflective to the IR (most things are),
then you are going to have no trouble. The power from the LED is
substantial and will totally flood the area with light. In that environment
it is not haphazard and will be very reliable.
If you have batteries in front and back, then you use 2 (or more) sets of
transceivers on the master.
The protocol has the master poll the battery modules. They don't talk
unless asked. They respond with their temperature, voltage, etc. and get
told when to enable the bypass load. If the master "goes away" for any
length of time, the load is removed.
The optoisolator with signal wiring seems less reliable to me, in an area
where you are likely to have acid fumes and "road" conditions. You'd need
to use sealed connectors, and that complicates things a bit. Not to mention
the danger of having extra wiring strung around the high-voltage potential
array.
The IR design can be potted in an IR transparent resin and then be very
mechanically and environmentally rugged. The potting mold can be built so
as to actually increase IR scattering and detection.
-Phil
----- Original Message -----
From: "Danny Miller" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Sunday, May 13, 2007 12:32 PM
Subject: Re: BMS (Battery Management System (Was: 1-Wire Expertise)
Ah, actually I was thinking IR like 38KHz TV remotes, not specifically
IRDA.
You do generally need LOS. Just doing it in an enclosure without LOS
expecting reflections to carry it is very haphazard. Differences in
interior color make huge differences as does angling of the transmitter.
Any incidental sunlight can potentially overwhelm a receiver. Making it
so 10 transmitter-receivers can all see each other would be pretty darn
difficult. If one node can't receive from others even though its
transmitter could be seen by others, it might transmit during the same
time as the others. Depending on your protocol it might well be possible
for a node to figure out when it should xmit even though it could only
receive a coherent signal from one or two others.
So looking at all the things that can (and almost certainly will) go
wrong, just one gnd and one signal wire doesn't sound too hard to route to
each device.
Danny
(-Phil-) wrote:
Note, I didn't specify IIRDA!
I recommend 40khz IR. Same stuff used in consumer electronics for remote
controls. You don't need LOS. No cabling and you can pot the whole
assembly so no battery acid can get on your board or the data connectors.
Only cabling in the battery box will then be the primary wiring.
-Phil
----- Original Message ----- From: "Danny Miller" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Sunday, May 13, 2007 12:04 PM
Subject: Re: BMS (Battery Management System (Was: 1-Wire Expertise)
I don't think there's any practicality to using IRDA. You generally
need a straight line-of-sight.
Again, the 1-wire protocol CAN be adapted to an isolated scheme,
however, no commercially available device will implement it. You'd need
to write up an implementation. It just takes a controller (PIC) and two
optoisolators (might be $1 or $2). So you can power a PIC voltage
sensor with the battery voltage and then communicate that across the
isolated bus.
There's a question of how much power the sensor draws. It's not much
but the important problem here is that with one hooked up to each batt
it's generally impractical to disconnect each one when you're not
driving. The PIC may be able to go into SLEEP mode and its current goes
way into inconsequential. However, the typical voltage divider must
remain powered and that draws about 2.5mA. The optoisolator's receiving
side also has a nonzero "dark current" when the receiving side is
powered even if it's at the "off" level.
Well, 2.5mA isn't a particularly big problem. It would take months to
use a substantial portion of the batt capacity.
The boards should logically integrate the charging regs on-board, since
we're already building one per batt.
Danny
(-Phil-) wrote:
I used the TSOP1740 in a project a few years ago. I think I bought 100
of them for about 40 cents each. Pretty cheap!
http://www.vishay.com/docs/82030/82030.pdf
You may be thinking of FastIR/IRDA or similar. Too costly, and no need
to invoke the complex protocols.
The Micros can be very small/low power. The protocol is very simple
because of the low data rate requirement. I can do it in a few hundred
lines of assembly code, and run it on a ring-clocked low power micro.
It's probably easier, cheaper, and more reliable to use IR rather than
visible. The components ate cheap, and the modulated IR will bounce
better and not suffer as many from problems from interference. They
work fine even in the presence of sunlight.
If I build it, I will open-source it. Hurray if others want to build
them using my code! If more DIY EV'ers had a BMS, we'd save a lot of
batteries!
-Phil
----- Original Message ----- From: "Lee Hart" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Saturday, May 12, 2007 2:26 AM
Subject: Re: BMS (Battery Management System (Was: 1-Wire Expertise)
This is a good idea, Phil. I've used visible light in a battery box,
and it worked pretty well. The box had white styrofoam lining it, and
the light bounced around nicely, so a single sensor could see the
light from any sender.
I wonder about the cost, though. The IR receivers I see cost dollars,
not pennies. Do you have any examples in mind? Also, the micro may
need to be more powerful than you think; network protocols often
require a large amount of computing resources.
An open source project is a worthy goal, but too often people use the
name to mean, "I want somebody else to develop it for me for free."
I'm not sure how to inspire a group of people to work together on such
a project.
--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377,
leeahart_at_earthlink.net
(¤Phil¤) wrote:
Seems like the right thing to do is put a little board on each
battery. The board would contain a small microcontroller with ADC, a
IR LED, a monolithic IR receiver (like those used in consumer
electronics to receive remote control signals), a high-current MOSFET
and a resistor (light bulb?). The board would only hook to (+) and
(-) of each battery in the array. No data cabling. 2 wires, that's
it.
The units would all be identical, but contain a unique serial number
in the firmware. A central controller would then poll the individual
units via 40khz IR signals. The units would respond the same way.
The central controller can then order the load on and off for
equalization of the pack when charging.
The IR effectively galvanically isolates the whole mess and makes it
unlikely an accident could occur. The IR would readily bounce all
around battery enclosures and make a reliable 2-way communication
system with no wires and very low cost. The IR LED/Receiver are
commodity items and cost pennies.
The little boards would thus be cheap and easy to make, and very safe
with no possibility of shorts, etc.
Open-source the firmware and PCB design. Maybe a group-buy of the
little PCBs.
--- End Message ---
--- Begin Message ---
Yes, they likely would if it was high, and they don't for at least 2
reasons:
First is that most of the magnetic fields in the motor STAY in the motor!
This is done to prevent magnetic loss and increase efficiency. Nothing new!
Second is that EM fields are bound by the "Distance Squared" principle of
physics. Distance causes a exponential loss.
Also; many Hall-effect "pot" boxes are also magnetically shielded!
-Phil
----- Original Message -----
From: "Jeff Shanab" <[EMAIL PROTECTED]>
To: "Electric Vehicle Discussion List" <ev@listproc.sjsu.edu>
Sent: Sunday, May 13, 2007 1:47 PM
Subject: Re: magnetic field in EV car?
I just thought of something, If the magnetic field was large, wouldn't
those with hall effect go pedals would have problems?
--- End Message ---
--- Begin Message ---
Richard is an acquaintance of mine, and I am the only authorized repair
depot for his products in the US.
He is an amazing engineer!
-Phil
----- Original Message -----
From: "tt2tjw" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Sunday, May 13, 2007 12:20 PM
Subject: Re: Sepex regen
thanks phil, I quite often read articles from 4qd, I will look again for
inductance.
(-Phil-) wrote:
For an interesting bunch of reading on motor controllers, and many things
EV related, check out Richard Torrens' excellent site:
http://4qd.co.uk/faq/index.html
Tons of great reading, and explanations on things like how the motor
inductance is used to act as a boost during regen.
-Phil
----- Original Message ----- From: "tt2tjw" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Sunday, May 13, 2007 11:08 AM
Subject: Re: Sepex regen
Ok thanks again George, I'm off to read about inductance then hopefully
I will understand a little better how it works and how to choose the
duty value.
George Swartz wrote:
In PWM boost, the low side IGBT turns on and builds up armature
current. When it turns off, the "flywheel" effect of the armature
inductance causes current to keep flowing thru a blocking diode and
back into the battery. (The current waveform is a two slope, and
roughly triangular at 50% duty cycle) This flyback current would flow
up to any practical battery voltage.
At very low motor voltages, the boost becomes inefficient, but
electrical braking remains good, as energy is dissipated in the motor
windings.
Sometimes, an external inductor is used to add inductance to the motor.
This is particularly true for a sepex motor since it has no series
field to add to motor inductance. The external inductor makes both the
boost and run more efficient.
The flyback diode could be the inverse parallel diode associated with
the upper IGBT, or could be an added diode?
On Sun, 13 May 2007 17:39:12 +0100, tt2tjw wrote
Thanks for your help George, I think I partially understand it now
I originally stupidly thought that at low rpm there was too high a
voltage, in actual fact there is too little volts to charge the
battery.
I am still a little confused though, how does the chopper boost the
voltage?
I can have a guess based on what I can see in the controller;
This is how the controller is set up:
the IGBT driving the armature is a half bridge C1 is connected to +ve
battery
E1/C2 is connected to one of the armature terminals
E2 is connected to the other armature terminal and to the -ve battery
terminal there are the usual free wheel diodes between E2 and E1/C2
and between E1/C2 and C1
As far as I can see:
when the battery is driving the motor the low side is turned off and
the high side is chopping (up to 1500rpm, thereafter the high side is
full on) in high rpm regen both the high and the low side are turned
off in low rpm regen the high side is off and I think the low side
must chop.
In low rpm regen when the low side is on the current will flow though
the low side IGBT and back through the armature. Does this somehow
increase the voltage in the armature untill it is large enough to
charge the battery?
What would happen if the low side didn't chop?
George Swartz wrote:
You need both. The chopper is probably a "shunt" boost chopper which
is
in
parallel with the motor and is used when the motor back emf is less
than
the
battery voltage. The chopper boosts the lower motor voltage up to
the battery voltage. Regen braking is strong and effective down to
low
speed,
like 3 mph or so. At high speeds, if you used a chopper, it would
have
to
be in a series configuration with the batteries, assuming you were
stuck with full field. It is easy to use field control in the sepex
motor for regen above base speed.
On Sun, 13 May 2007 15:45:35 +0100, tt2tjw wrote
Does anyone know why it might be neccessary to chop the regen
current on a sepex motor?
Below is my understanding, do other people think this is correct?
I can see that the regen current/volts must be limited to avoid
cooking the batteries.
It seems to me that at high rpm this can be achieved by varying the
field current until max field current is reached (which for my motor
is about 1500 rpm or about 15mph). As the rpm drops below this
level one way to limit the regen current would be to open the main
contactor, presumably this is not something one would want to do on
a regular basis and so the regen current is chopped.
If my understanding is correct the brake chopper only needs to work
below 1500rpm, though it could also be used at higher rpm. At higher
rpm which method is better, varying the field current or chopping
the regen current?
--- End Message ---
--- Begin Message ---
To me, the thing we should be looking at is not the motor, but the wiring!
If you look at the national electrical code, they have all kinds of weird
(to most electricians) requirements when dealing with inverter driven
motors. This is becoming the standard in industrial automation.
VFD/Inverter drives are getting cheaper and it makes sense even if you are
just using it as a way to soft-start the motor for energy savings.
The reason is the relatively high frequencies involved (the same as in a
modern EV controller) can interact with the little inductance created by not
keeping the transmission lines together. You get eddy currents, induced
voltages, and all kinds of nasties by not installing your high-power
high-frequency transmission lines in a proper way. Try running any kind of
sensitive signal wiring near the controller to motor wiring and you will see
what I mean. It quickly can inductively couple relatively large voltages
into the signal wiring and cause many problems. Bad wiring practice can
cause controller reboots, sudden breaker/fuse trips, spontaneous controller
failure, excessive brushgear arcing, etc.
Excessive inductance, even a "one turn" loop in the battery to controller
wiring can cause high heat to build up in the controller!
Here is Richard's information on this:
http://4qd.co.uk/serv/appnotes/machinewire.html
-Phil
----- Original Message -----
From: "(-Phil-)" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Sunday, May 13, 2007 2:36 PM
Subject: Re: magnetic field in EV car?
Yes, they likely would if it was high, and they don't for at least 2
reasons:
First is that most of the magnetic fields in the motor STAY in the motor!
This is done to prevent magnetic loss and increase efficiency. Nothing
new!
Second is that EM fields are bound by the "Distance Squared" principle of
physics. Distance causes a exponential loss.
Also; many Hall-effect "pot" boxes are also magnetically shielded!
-Phil
----- Original Message -----
From: "Jeff Shanab" <[EMAIL PROTECTED]>
To: "Electric Vehicle Discussion List" <ev@listproc.sjsu.edu>
Sent: Sunday, May 13, 2007 1:47 PM
Subject: Re: magnetic field in EV car?
I just thought of something, If the magnetic field was large, wouldn't
those with hall effect go pedals would have problems?
--- End Message ---
--- Begin Message ---
On 5/13/07, Jay Caplan <[EMAIL PROTECTED]> wrote:
Math correction
> $2.75/lb. The amount
> of lithium metal in lithium carbonate is about 11/58. So that brings
> the Lithium metal cost to about $80 per lb (per 453.59 g).
Li2CO3 is mol wt 74. The Li2 is 14 mol wt
So, the fraction is 14/74 of lithium as fraction of lithium carbonate
$2.75 divided by 14 x 74 = $14.5/lb of lithium metal, not $80
> So, a 50AH Lithium cell has ~15g of Lithium metal in it. Which comes
> out to about $2.65.
15 divided by 453 x $14.50 = $0.48 of lithium in the 50AH battery, not $2.65
JLC
Thanks muchly. Well, I got the 11/58 from a US resources report that
said that for 58 million metric tons of Lithium Carbonate there was a
yield of 11 million metric tons of Lithium metal. Perhaps they are
accounting for processing losses?
Also.. I can't believe I made that math error! Well.. I suppose
arithmetic is the first to go when you have a Math degree ;)
The good news is that I made the mistake in the bad direction.. the
actual price is LOWER. :)
Interesting, no?
--T
--- End Message ---
--- Begin Message ---
I believe you might be confusing voltage and current.
Too much curent is what over heats motors and demagnetises magnets.
Raising the voltage just makes the motor spin faster, if you pay attention
to the current and keep it in specs. Of course you also have to pay
attention to the RPM to prevent the motor from flying apart.
You have to pay attention to the current anyway, it's possible to pump to
much current through a 48V motor even if you are only running 36V.
> Oh, I forgot to say, the reason I said non-PM is because if you overdrive
> a
> PM motor, you can actually demagnetize or depolarize the magnets!
>
> -Phil
> ----- Original Message -----
> From: "(-Phil-)" <[EMAIL PROTECTED]>
> To: <ev@listproc.sjsu.edu>
> Sent: Sunday, May 13, 2007 11:38 AM
> Subject: Re: How does a 48v motor handle higher voltages?
>
>
>> Typically a 48v motor (non-PM) can withstand 96v for short durations.
>> Keep it cool and you can do a lot of abusing! Too high of power and you
>> may fry the brushgear/commutator though.
>>
>> I've even heard of people sealing the motors up and immersing them in
>> oil.... You'll get friction from the oil shear, but if you have an oil
>> cooler, it's definitely going to say cool!
>>
>> Some large truck and bus alternators are cooled in this way also.
>>
>> The Prius uses oil-cooled motors, and they are tiny! 600 volts!
>>
>> Tell him you are going to add oil cooling.... =)
>>
>> -Phil
>> ----- Original Message -----
>> From: "childreypa" <[EMAIL PROTECTED]>
>> To: <ev@listproc.sjsu.edu>
>> Sent: Sunday, May 13, 2007 10:08 AM
>> Subject: How does a 48v motor handle higher voltages?
>>
>>
>>> I've been calling some forklift places trying to find an old motor that
>>> I can use to get my project going. I am looking for a large forklift
>>> motor at 48v. I mentioned that this was for an electric vehicle running
>>> greater than 96v. The man said I couldn't do this. A 48v motor can only
>>> handle 48v. This makes perfect sense but I know people use them in
>>> EV's.
>>> Is it the better cooling these motors receive in a car? Advancing the
>>> brushes? Maybe the motor has to be rewound? Maybe the life is severely
>>> deminished? How do I answer an oldtimer who knows plenty more than me
>>> about motors that I want to use a 48v motor in an EV?
>>> Thanks,
>>> Paul
>>>
>>>
>>
>>
>
>
--
If you send email to me, or the EVDL, that has > 4 lines of legalistic
junk at the end; then you are specifically authorizing me to do whatever I
wish with the message. By posting the message you agree that your long
legalistic signature is void.
--- End Message ---
--- Begin Message ---
You could always try fiber optics to connect all of the IR sensors to all
of the IR emitters.
> Ah, actually I was thinking IR like 38KHz TV remotes, not specifically
> IRDA.
>
> You do generally need LOS. Just doing it in an enclosure without LOS
> expecting reflections to carry it is very haphazard. Differences in
> interior color make huge differences as does angling of the
> transmitter. Any incidental sunlight can potentially overwhelm a
> receiver. Making it so 10 transmitter-receivers can all see each other
> would be pretty darn difficult. If one node can't receive from others
> even though its transmitter could be seen by others, it might transmit
> during the same time as the others. Depending on your protocol it might
> well be possible for a node to figure out when it should xmit even
> though it could only receive a coherent signal from one or two others.
>
> So looking at all the things that can (and almost certainly will) go
> wrong, just one gnd and one signal wire doesn't sound too hard to route
> to each device.
>
> Danny
>
> (-Phil-) wrote:
>
>> Note, I didn't specify IIRDA!
>>
>> I recommend 40khz IR. Same stuff used in consumer electronics for
>> remote controls. You don't need LOS. No cabling and you can pot the
>> whole assembly so no battery acid can get on your board or the data
>> connectors. Only cabling in the battery box will then be the primary
>> wiring.
>>
>> -Phil
>> ----- Original Message ----- From: "Danny Miller" <[EMAIL PROTECTED]>
>> To: <ev@listproc.sjsu.edu>
>> Sent: Sunday, May 13, 2007 12:04 PM
>> Subject: Re: BMS (Battery Management System (Was: 1-Wire Expertise)
>>
>>
>>> I don't think there's any practicality to using IRDA. You generally
>>> need a straight line-of-sight.
>>> Again, the 1-wire protocol CAN be adapted to an isolated scheme,
>>> however, no commercially available device will implement it. You'd
>>> need to write up an implementation. It just takes a controller (PIC)
>>> and two optoisolators (might be $1 or $2). So you can power a PIC
>>> voltage sensor with the battery voltage and then communicate that
>>> across the isolated bus.
>>>
>>> There's a question of how much power the sensor draws. It's not much
>>> but the important problem here is that with one hooked up to each
>>> batt it's generally impractical to disconnect each one when you're
>>> not driving. The PIC may be able to go into SLEEP mode and its
>>> current goes way into inconsequential. However, the typical voltage
>>> divider must remain powered and that draws about 2.5mA. The
>>> optoisolator's receiving side also has a nonzero "dark current" when
>>> the receiving side is powered even if it's at the "off" level.
>>>
>>> Well, 2.5mA isn't a particularly big problem. It would take months
>>> to use a substantial portion of the batt capacity.
>>>
>>> The boards should logically integrate the charging regs on-board,
>>> since we're already building one per batt.
>>>
>>> Danny
>>>
>>> (-Phil-) wrote:
>>>
>>>> I used the TSOP1740 in a project a few years ago. I think I bought
>>>> 100 of them for about 40 cents each. Pretty cheap!
>>>> http://www.vishay.com/docs/82030/82030.pdf
>>>>
>>>> You may be thinking of FastIR/IRDA or similar. Too costly, and no
>>>> need to invoke the complex protocols.
>>>>
>>>> The Micros can be very small/low power. The protocol is very
>>>> simple because of the low data rate requirement. I can do it in a
>>>> few hundred lines of assembly code, and run it on a ring-clocked low
>>>> power micro.
>>>>
>>>> It's probably easier, cheaper, and more reliable to use IR rather
>>>> than visible. The components ate cheap, and the modulated IR will
>>>> bounce better and not suffer as many from problems from
>>>> interference. They work fine even in the presence of sunlight.
>>>>
>>>> If I build it, I will open-source it. Hurray if others want to
>>>> build them using my code! If more DIY EV'ers had a BMS, we'd save
>>>> a lot of batteries!
>>>>
>>>> -Phil
>>>> ----- Original Message ----- From: "Lee Hart" <[EMAIL PROTECTED]>
>>>> To: <ev@listproc.sjsu.edu>
>>>> Sent: Saturday, May 12, 2007 2:26 AM
>>>> Subject: Re: BMS (Battery Management System (Was: 1-Wire Expertise)
>>>>
>>>>> This is a good idea, Phil. I've used visible light in a battery
>>>>> box, and it worked pretty well. The box had white styrofoam lining
>>>>> it, and the light bounced around nicely, so a single sensor could
>>>>> see the light from any sender.
>>>>>
>>>>> I wonder about the cost, though. The IR receivers I see cost
>>>>> dollars, not pennies. Do you have any examples in mind? Also, the
>>>>> micro may need to be more powerful than you think; network
>>>>> protocols often require a large amount of computing resources.
>>>>>
>>>>> An open source project is a worthy goal, but too often people use
>>>>> the name to mean, "I want somebody else to develop it for me for
>>>>> free." I'm not sure how to inspire a group of people to work
>>>>> together on such a project.
>>>>>
>>>>> --
>>>>> Ring the bells that still can ring
>>>>> Forget the perfect offering
>>>>> There is a crack in everything
>>>>> That's how the light gets in -- Leonard Cohen
>>>>> --
>>>>> Lee A. Hart, 814 8th Ave N, Sartell MN 56377,
>>>>> leeahart_at_earthlink.net
>>>>>
>>>>>
>>>>> (¤Phil¤) wrote:
>>>>>
>>>>>> Seems like the right thing to do is put a little board on each
>>>>>> battery. The board would contain a small microcontroller with ADC,
>>>>>> a IR LED, a monolithic IR receiver (like those used in consumer
>>>>>> electronics to receive remote control signals), a high-current
>>>>>> MOSFET and a resistor (light bulb?). The board would only hook to
>>>>>> (+) and (-) of each battery in the array. No data cabling. 2
>>>>>> wires, that's it.
>>>>>>
>>>>>> The units would all be identical, but contain a unique serial
>>>>>> number in the firmware. A central controller would then poll the
>>>>>> individual units via 40khz IR signals. The units would respond
>>>>>> the same way. The central controller can then order the load on
>>>>>> and off for equalization of the pack when charging.
>>>>>>
>>>>>> The IR effectively galvanically isolates the whole mess and makes
>>>>>> it unlikely an accident could occur. The IR would readily bounce
>>>>>> all around battery enclosures and make a reliable 2-way
>>>>>> communication system with no wires and very low cost. The IR
>>>>>> LED/Receiver are commodity items and cost pennies.
>>>>>>
>>>>>> The little boards would thus be cheap and easy to make, and very
>>>>>> safe with no possibility of shorts, etc.
>>>>>>
>>>>>> Open-source the firmware and PCB design. Maybe a group-buy of the
>>>>>> little PCBs.
>>>>>
>>>>>
>>>>
>>>
>>>
>>
>
>
--
If you send email to me, or the EVDL, that has > 4 lines of legalistic
junk at the end; then you are specifically authorizing me to do whatever I
wish with the message. By posting the message you agree that your long
legalistic signature is void.
--- End Message ---
--- Begin Message ---
Hi,
> You're absolutely right about the functional part of the Open Source
> equation.. in this case not just Open Source (code) but Open
> Development in general. However almost every Open Source success is
> defined by a small group of evangelists who make something really
> great and share it, after which people start hopping 'on the
> bandwagon' because the solution scratched a particular itch. Linux
> overall, and the Apache web server are two great examples.
>
> I would suggest that the best way to do this is to gather a small
> core
> of interested parties, building resources, and seeing if 'they come'.
> :) Over time you can enlist the aid of experts on specific items that
> might need some noodling, but generally it is enthusiasts that drive
> these sorts of projects.
I was trying to point out that in our case, the experts already exist
as members of the EV list. There are many "evangelists" among them
who would love to participate, but lack the programming skills to build
the infrastructure. But they *will* need to be involved in the
selection of CAD tools, etc.
> Also, given the nature of this animal I see no trouble in using the
> GPL, and great advantages since people won't be tempted just to rip
> things off wholesale, refer to the OpenEV site as authoritative, but
> having changed some things to be inferior for profit purposes, thus
> damaging the rep of the project. With the GPL people are free to sell
> everything but they have to make the plans and source code available
> to end users, in adfinitum. That protects them, the end users and the
> OpenEV site.
I personaly prefer the modified BSD license, if for nothing else, its
simplicity. I could live with GPL, especially if libraries are tagged
with LGPL (lesser GPL).
> I've registered OpenEV.org as well, and I think this could be
> fantastic! The rough spots are only where the rubber meets the road
> in
> IP, hence why you have to be REALLY clear with respect to how the
> stuff is lisenced. Since you are also dealing with patentable
> concepts, everything needs to be completely open to avoid someone
> patenting things out from under you... your site would be prior art
> and thus invalidate the patent claim (someone pls correct me if I am
> incorrect here). Etc etc.
Eventually, the "project" would have to own any domain used to
house itself. Would you be willing to transfer "OpenEV.org"
once the project was incorporated as a non-profit?
---
Steve
____________________________________________________________________________________Luggage?
GPS? Comic books?
Check out fitting gifts for grads at Yahoo! Search
http://search.yahoo.com/search?fr=oni_on_mail&p=graduation+gifts&cs=bz
--- End Message ---
--- Begin Message ---
> I saw an Porsche 914 EV conversion a few years back and the front battery
> wiring had been passed through the rocker boxes on either side of the
> passenger compartment. One wire on each side! That turns the passenger
> compartment into a huge air-core inductor! The capacitors failed in his
> Curtis in short order and cooked the controller, and he didn't believe
> that
> routing the battery wires in such a way could have caused the problem,
> despite my insistence.
Did you ever calculate the inductance of this "huge air-core inductor"?
Assuming the cables were 0000 ga and approx 3 meters long, I get 3.7uH
inductance in each wire. That is ignoring the metal enclosure. If we
assume the rocker panels act as a ground plane, then we get about 0.1uH
The effect on inductance of two such wires spaced over a meter and a half
apart and running through magnetically shielded tunnels is beyond my
knowledge to calculate, but I'd estimate it to be so small as to have no
real effect.
The problem here is simply the self inductance of the wires. Running the
two wires through the same rocker panel would be better, because the two
wires will (mostly) cancel out each others inductance as well as adding a
bit of capacitance (which is good in this application)
>
> FYI: Whenever you run battery or motor wiring, try to keep the wires as
> close as possible to each other, even twist them if possible. If they run
> through the passenger compartment, run them in a metallic conduit.
> Whatever
> you do, Don't run each wire through it's own conduit! You can end up
> inducing a large eddy current in the conduits...
>
> -Phil
> ----- Original Message -----
> From: "JS" <[EMAIL PROTECTED]>
> To: <ev@listproc.sjsu.edu>
> Sent: Sunday, May 13, 2007 8:28 AM
> Subject: RE: EMF in EVs
>
>
>> Everything old is new again:
>> About 1959 I was involved in a bio-magnetic research project.
>> We found an obscure research project IIRC by Thompson about 1906.
>> He studied workers around large transformers in the power industry,
>> and found no effects.
>>
>> EV's were popular in that time frame.
>> John in Sylmar, CA
>> PV EV
>>
>>
>
>
--
If you send email to me, or the EVDL, that has > 4 lines of legalistic
junk at the end; then you are specifically authorizing me to do whatever I
wish with the message. By posting the message you agree that your long
legalistic signature is void.
--- End Message ---
--- Begin Message ---
So, instead of programming for a constant speed, you could program for
constant current, and let the speed vary as it would?
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Roland Wiench
Sent: Sunday, May 13, 2007 2:30 PM
To: ev@listproc.sjsu.edu
Subject: Re: Vehicle efficiency, wh/mile - cruise control
If you was on a dead level grade, cruise controls works, as it does in my
other cars, but in hilly country while going up a grade, you can feel more
power being added which is pushing the accelerator harder, and going down
hill, it holds you back.
I make more range, while holding the accelerator at a constant pressure
which may slow you up a bit, and let it get up to a high as a speed as
possible while coasting down a grade.
At one time we did not have a speed limit, now it is 79 mph, (4 miles over),
where at times a vehicle may get up to over 85 mph going down hill, which I
therefore can roller coast up the next which slows the vehicle to about 60
mph going up the next grade.
I was be able to coast all the way from my work place all the way into my
garage which was about 5 miles.
I now have too many short runs of about 1/2 mile long with only one stop at
the end of each run. It's like driving on a very long 3 to 5 mile long
connected parking lot.
Roland
----- Original Message -----
From: "Tehben Dean" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Sunday, May 13, 2007 12:03 PM
Subject: Re: Vehicle efficiency, wh/mile - cruise control
> It seems like cruise control would be very easy to build into an EV
> controller... its all electronic.
> Wonder why its not done... or is it?
>
> On May 13, 2007, at 6:49 AM, [EMAIL PROTECTED] wrote:
>
> >
> > Roland> One way I found that can reduce the AH or wh usage is if
> > Roland> everything else is perfect, is the amount of pressure you
> > Roland> maintain on the accelerator. For example, to accelerate
> > my EV up
> > Roland> to a certain speed, I just press the accelerator just
> > to that
> > Roland> point which will maintain that speed, not push it to
> > the floor
> > Roland> and then when you get to the speed you want, then let
> > up on the
> > Roland> accelerator at that point.
> >
> > Seems like cruise control would be very helpful in an EV.
> >
> > --
> > Skip Montanaro - [EMAIL PROTECTED] - http://www.webfast.com/~skip/
> >
>
>
--- End Message ---
--- Begin Message ---
>> Thank you for actually reading my posts Tehben
>
> No problem ;)
>
> Again I personally have not come to a conclusion either way as to the
> safety of manmade electromagnetic fields.
Me neither.
But I think that looking for a cancer link is the extreme and catastrophic
case. Lets put it this way, does it really have to cause cancer to start
taking the other studies seriously. As far as I am concerned, I read all
the studies that come my way that talk about measurable effects on
biological systems due to EM field, good or bad. I find it very
interesting to see how living systems are affected in whatever way by
electromagnetic fields. I don't necessarily think and wait for
catastrophic findings to keep up my interest. There are more sublte
effects like cell membrane permeability to various ions. That one is
easily reproducible. If one really pays interest to this field, one can
find literaly hundreds of recent studies that show sublte effect of EM
fields on animals and cell cultures. And the power content of the EM field
most often has nothing to do with the measurable effect. Like you said
before, frequency has more effect than the power level.
If we ever find such terrible link between em fields and cancer. It will
be extremely difficult if not impossible to back track our usage of those
fields. We will have to look at the cost/benefit ratio just like we do
when we decide to drive a car and assume the risk of an accident.
Best Regards,
--
Patrick Robin
http://atelierrobin.net
--- End Message ---
--- Begin Message ---
Constant current on the battery side or the motor side?
On the battery side you'd have trouble on hills as the vehicle slows WAY
down. You'd end up going up the hill very slowly while the motor was
drawing lots of current and overheating.
If you maintained constant motor current, you'd slow down even more going
up hill until you came to a stop and then fried your commutator.
Constant voltage on the motor side is somewhat better as you'd maintain a
somewhat even speed, but it might not be as efficient.
Unless you are going to use a computer controlled system with a really
good algorythm, your best method is to use a well programmed human to
control the system.
> So, instead of programming for a constant speed, you could program for
> constant current, and let the speed vary as it would?
>
>
>
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
> Behalf Of Roland Wiench
> Sent: Sunday, May 13, 2007 2:30 PM
> To: ev@listproc.sjsu.edu
> Subject: Re: Vehicle efficiency, wh/mile - cruise control
>
> If you was on a dead level grade, cruise controls works, as it does in my
> other cars, but in hilly country while going up a grade, you can feel more
> power being added which is pushing the accelerator harder, and going down
> hill, it holds you back.
>
> I make more range, while holding the accelerator at a constant pressure
> which may slow you up a bit, and let it get up to a high as a speed as
> possible while coasting down a grade.
>
> At one time we did not have a speed limit, now it is 79 mph, (4 miles
> over),
>
> where at times a vehicle may get up to over 85 mph going down hill, which
> I
> therefore can roller coast up the next which slows the vehicle to about 60
> mph going up the next grade.
>
> I was be able to coast all the way from my work place all the way into my
> garage which was about 5 miles.
>
> I now have too many short runs of about 1/2 mile long with only one stop
> at
> the end of each run. It's like driving on a very long 3 to 5 mile long
> connected parking lot.
>
> Roland
>
>
> ----- Original Message -----
> From: "Tehben Dean" <[EMAIL PROTECTED]>
> To: <ev@listproc.sjsu.edu>
> Sent: Sunday, May 13, 2007 12:03 PM
> Subject: Re: Vehicle efficiency, wh/mile - cruise control
>
>
>> It seems like cruise control would be very easy to build into an EV
>> controller... its all electronic.
>> Wonder why its not done... or is it?
>>
>> On May 13, 2007, at 6:49 AM, [EMAIL PROTECTED] wrote:
>>
>> >
>> > Roland> One way I found that can reduce the AH or wh usage is if
>> > Roland> everything else is perfect, is the amount of pressure you
>> > Roland> maintain on the accelerator. For example, to accelerate
>> > my EV up
>> > Roland> to a certain speed, I just press the accelerator just
>> > to that
>> > Roland> point which will maintain that speed, not push it to
>> > the floor
>> > Roland> and then when you get to the speed you want, then let
>> > up on the
>> > Roland> accelerator at that point.
>> >
>> > Seems like cruise control would be very helpful in an EV.
>> >
>> > --
>> > Skip Montanaro - [EMAIL PROTECTED] - http://www.webfast.com/~skip/
>> >
>>
>>
>
>
>
>
--
If you send email to me, or the EVDL, that has > 4 lines of legalistic
junk at the end; then you are specifically authorizing me to do whatever I
wish with the message. By posting the message you agree that your long
legalistic signature is void.
--- End Message ---
--- Begin Message ---
My car averages 180Wh/km or 288Wh/mile wall to road.
That equates to about two thirds the CO2 emissions of an equivalent
IC car.
However I can also run my car directly from the sun ;-)
Regards, Rod Dilkes
On 14/05/2007, at 2:19 AM, Electric Vehicle Discussion List wrote:
From: Ian Hooper <[EMAIL PROTECTED]>
Date: 13 May 2007 5:32:37 PM
To: ev@listproc.sjsu.edu
Subject: Vehicle efficiency, wh/mile
Hi all,
I was just curious if many people on the list have measured their
EV's efficiency i.e average watt-hours per mile?
I've heard figures around 300wh/mile thrown around, but that seems
like a fair bit of energy to me.. Could that be based on people
using the C20 capacity of lead acid to calculate the pack's energy?
-Ian
--- End Message ---
--- Begin Message ---
What study is this?
Most of those studies which have found a significant effect did so by
using absurdly high field strengths. Fairly close to putting the lab
rats a microwave oven. While I'm sure this is an interesting case for
someone, it's not likely to be applicable to everyday use.
Danny
Patrick Robin wrote:
There are more sublte
effects like cell membrane permeability to various ions. That one is
easily reproducible. If one really pays interest to this field, one can
find literaly hundreds of recent studies that show sublte effect of EM
fields on animals and cell cultures. And the power content of the EM field
most often has nothing to do with the measurable effect. Like you said
before, frequency has more effect than the power level.
If we ever find such terrible link between em fields and cancer. It will
be extremely difficult if not impossible to back track our usage of those
fields. We will have to look at the cost/benefit ratio just like we do
when we decide to drive a car and assume the risk of an accident.
Best Regards,
--- End Message ---
