LithiumBMS-In the interest of saving time & money I spent more of both

[AMPhibian]

Peter C. Thompson wrote

Hi David,

Interesting points, but they are all supposition.  What we don't have is
hard facts, I think we can agree on that point.  :)
 

The only hard facts we do have are that BMS modules have failed and in doing so have drained cells and permanently damaged them.  Are newer modules physically incapable of doing the same?

[Mark Grasser]

 
>>>The only hard facts we do have are that BMS modules have failed and in
doing
so have drained cells and permanently damaged them.  Are newer modules
physically incapable of doing the same?<<<


I would like to think that as the BMS improves it would get to the level of
excellence of any other product out there. I know I am working on a BMS that
if given enough engineering time should be next to perfect.

Mark Grasser

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[Myles Twete]

Hmm... your confidence in technology is impressive.
Individual PbA battery chargers have been around for a long time now and
many EV'ers have adopted their use in charging batteries in strings.  Yet
how few cases have there been where you've heard someone say they have never
had a problem with at least one of these chargers over the life of their
batteries?  Even suppliers with a great reputation for building quality
chargers sell duds.  That alone should make one think twice about trusting
any particular BMS without reviewing its success rate.


-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf
Of Mark Grasser
Sent: Thursday, May 12, 2011 6:24 PM
To: 'Electric Vehicle Discussion List'
Subject: Re: [EVDL] LithiumBMS-In the interest of saving time & money I
spent more of both

 
>>>The only hard facts we do have are that BMS modules have failed and in
doing
so have drained cells and permanently damaged them.  Are newer modules
physically incapable of doing the same?<<<


I would like to think that as the BMS improves it would get to the level of
excellence of any other product out there. I know I am working on a BMS that
if given enough engineering time should be next to perfect.

Mark Grasser

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[David Dymaxion]

Mark, thank you for disclosing that you are developing a BMS, and I wish you
success. Just a thought, researching and embracing the burned car stories may be
to your business benefit. You could then market how your BMS would have better
safety features (like a pulse that says everything is OK, no pulse = assume the
worst) than the competition. Note this does not say any BMS caused or didn't
cause the fires, you could say how yours would prevent fires even in the cases
of user error or charger malfunction.

My disclaimer: I do not stand to financially profit by the success or failure of
any BMS retailer.

FWIW, I have been designing my own BMS, too, though I don't have any plans to
market it. My design converged on something similar to Lee Hart's battery
balancer design.

Also FWIW, my own limited testing
( http://explodingdinosaurs.com/9electric/celltest ) showed the batteries stayed
in close balance without a BMS, at least until one vented!

Don't fire off a reply yet, another post is coming!




________________________________
From: Mark Grasser <[hidden email]>
To: Electric Vehicle Discussion List <[hidden email]>
Sent: Thu, May 12, 2011 7:24:11 PM
Subject: Re: [EVDL] LithiumBMS-In the interest of saving time & money I spent
more of both


>>>The only hard facts we do have are that BMS modules have failed and in
doing
so have drained cells and permanently damaged them.  Are newer modules
physically incapable of doing the same?<<<


I would like to think that as the BMS improves it would get to the level of
excellence of any other product out there. I know I am working on a BMS that
if given enough engineering time should be next to perfect.
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[David Dymaxion]

It didn't take long to find these examples. I didn't try to work exhaustively,
just did it for a short time, so there well could be more. Here's the short
story:

7 with BMS
5 didn't say if BMS (I think likely had BMSs, but didn't say it explicitly)
0 (zero) that said no bms

All the fires were lithium cars. A note on RG's cars, I counted only 1 even
though 7 burned. Disclaimer: I know other things might have caused the fires.

If you throw out the middle case, you still get 7 lithium BMS cars burned and 0
no BMS lithiums cars burned. That begs multiple questions:

  o  More data is needed
  o  What is the ratio of BMS cars to non BMS cars
  o  What role, if any, are BMSs playing in these fires?

So please help me here, can anyone provide links to other lithium cars with no
BMS (or with BMS) that has burned? We could make this a living list.

The Elithion site itself says 2 of the fires had Elithion BMS systems, Neil
Young's LincVolt and Santa Rosa Junior College's Ford Focus EV conversion:
http://liionbms.com/blog/2011/03/ev-fires-and-bmss/
http://www.pressdemocrat.com/article/20110319/NEWS/110319406/1350?p=1&tc=pg&tc=ar


Chevy Volt has a BMS. It's not certain if the Volt or the converted Suzuki  
Samurai or something else caused the fire (the Samurai I don't think had lithium
batteries). The Volt later caught fire a 2nd time (but it was already fire
damaged at that point).
http://www.qualitychevy.com/2011-chevy-volt-news.html
http://detroit.cbslocal.com/2011/04/16/garage-fire-starts-debate-are-batteries-in-electric-cars-safe/

http://green.autoblog.com/2011/04/18/report-burnt-chevrolet-volt-mysteriously-catches-fire-again/


A converted Nissan in Europe. Jack Rickard examined personally an identical car
from the same converter, and it featured a REAP BMS.
http://ekstrabladet.dk/112/article1453404.ece
http://jackrickard.blogspot.com/2011_01_01_archive.html

Jack Rickard reported a fire on one of his cars with a cellLog8 battery
monitoring system:
http://jackrickard.blogspot.com/2010/11/itsy-bitsy-spyder-550-and-battery.html

Fiat 126 with an open source BMS:
http://www.batteryvehiclesociety.org.uk/forums/viewtopic.php?t=1825
http://www.evalbum.com/1529

A plug in Prius with a Hymotion system with a BMS:
http://priuschat.com/forums/prius-hybrid-news/51283-prius-a123-battery-fire-report.html

http://www.bloomberg.com/apps/news?pid=newsarchive&sid=aXZxl5AH9nqA&refer=japan
http://en.wikipedia.org/wiki/A123_Hymotion

Car with lithium and BMS burns while driving:
http://gm-volt.com/forum/archive/index.php/t-6370.html

Zotye lithium, it has "battery monitoring" but couldn't tell if it has cell or
block level BMS.
http://chinaautoweb.com/2011/04/hangzhou-halts-all-electric-taxis-as-a-zotye-langyue-multipla-ev-catches-fire/

http://www.usaelectricauto.com/vehicles/electric-vehicle.html

Reverend Gadget lost 7 conversions in a fire. He calls it "apparently an arson."
While he does use  lithium batteries and BMSs, I don't know how many of these
cars were lithium and which had BMSs. Can anyone help with that? The car of the
3rd link may or may not be one of the 7.
http://www.electric-cars-are-for-girls.com/electric-car-kit.html
http://www.revengeoftheelectriccar.com/_blog/The_Blog/post/Gadget%27s_New_World/
http://www.garagejournal.com/forum/showthread.php?t=72411

Three solar cars burned (implied they have lithium, doesn't say on BMS,  sounds
like they were not Lithium Iron Phosphate chemistry):
http://jcwinnie.biz/wordpress/?p=1788



________________________________
From: Mark Grasser <[hidden email]>
To: Electric Vehicle Discussion List <[hidden email]>
Sent: Thu, May 12, 2011 6:10:13 PM
Subject: Re: [EVDL] LithiumBMS-In the interest of saving time & money I spent
more of both

>>> I believe all of them had a BMS installed.<<<<

I believe is not "basis in facts" as I like to say. This argument has been
going on for months that "ALL EV fires involve BMSs" but no one is able to
prove that by listing all of the car fires and that in fact all of them had
BMSs. Then if that ever were to happen I don't see how that means that the
fire was caused by a BMS.

MY PERSPECTIVE would be that a lack of BMS on the pack would allow for cells
to go out of balance and some cells getting too much charge while others not
getting enough. This would for sure result in cell overcharge / overhear /
possible fire.

So, I am just saying that I have yet to see anyone making the comment "the
BMS did it" back that comment with fact.


Another comment you make is about the BMS being on top of a venting battery.
This should not be the cause of the BMS but actually a runaway  charger.

I need to leave this as I have gone too far already but this is the problem
as I see it: There are BMS manufacturers and charger manufacturers. The
problem you describe where the BMS starts a fire because of venting only
happens if the BMS were shunting so much current that it got hot enough to
create ignition and at the same time there was enough current still going
through the battery to make it vent. This is a problem of having a charger
for one reason or another not cutting back when the BMS started to bypass
current.

So what needs to be done: I think the EV industry needs to create a
"Standards Committee". Boating has it, RVing has it. I think it might be
time for thi list to consider creating a safety and engineering practices
committee. EVing has grown from a few smart engineers driving their own EVs
into a large group of people from engineers with talent all the way down to
individuals  that don't understand fusing and wire size much less inductance
and the concept of PWM.

To close this I would have to bet that most fires, BMS or no BMS are caused
by poor engineering, lack of fuses and just poor installation practices.
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[David Dymaxion]

> MY PERSPECTIVE would be that a lack of BMS on the pack would allow for
> cells to go out of balance ...

Mark, have you actually done a test to see if lithium cells go out of balance,
instead of just assuming it? You can get cheapy $10 cells for testing. Do a
string, put your bms on 1/2 of them, and run the other 1/2 without a BMS. I have
done a little testing (the batteries stayed well balanced without a BMS) and
plan to do more.


> Another comment you make is about the BMS being on top of a venting battery.
> This should not be the cause of the BMS but actually a runaway charger.

While this might generally be true, there could be cases where the charger isn't
running away but there still could be a fire. Suppose that cell's BMS board
wasn't working, and the cell got a little more overcharged each cycle, even
though the charger is working and terminating normally. What if a cell starts
venting (due to charge or discharge), and the melting or a bump or whatever
causes pack voltage to appear across the BMS board... seems this could cause a
spark that would start a fire. (BTW, it is unlikely surfaces would get hot
enough to ignite Ethyl Acetate, but a spark will ignite it.)

I agree with you that better practices and better design is needed. Tesla seems
to be doing fine -- we need to replicate that success rate with conversions.



________________________________
From: Mark Grasser <[hidden email]>
To: Electric Vehicle Discussion List <[hidden email]>
Sent: Thu, May 12, 2011 6:10:13 PM
Subject: Re: [EVDL] LithiumBMS-In the interest of saving time & money I spent
more of both

>>> I believe all of them had a BMS installed.<<<<

I believe is not "basis in facts" as I like to say. This argument has been
going on for months that "ALL EV fires involve BMSs" but no one is able to
prove that by listing all of the car fires and that infact all of them had
BMSs. Then if that ever were to happen I don't see how that means that the
fire was caused by a BMS.

MY PERSPECTIVE would be that a lack of BMS on the pack would allow for cells
to go out of balance and some cells getting too much charge while others not
getting enough. This would for sure result in cell overcharge / overhear /
possible fire.

So, I am just saying that I have yet to see anyone making the comment "the
BMS did it" back that comment with fact.


Another comment you make is about the BMS being on top of a venting battery.
This should not be the cause of the BMS but actually a runaway charger.

I need to leave this as I have gone too far already but this is the problem
as I see it: There are BMS manufacturers and charger manufacturers. The
problem you describe where the BMS starts a fire because of venting only
happens if the BMS were shunting so much current that it got hot enough to
create ignition and at the same time there was enough current still going
through the battery to make it vent. This is a problem of having a charger
for one reason or another not cutting back when the BMS started to bypass
current.

So what needs to be done: I think the EV industry needs to create a
"Standards Committee". Boating has it, RVing has it. I think it might be
time for thi list to consider creating a safety and engineering practices
committee. EVing has grown from a few smart engineers driving their own EVs
into a large group of people from engineers with talent all the way down to
individuals that don't understand fusing and wire size much less inductance
and the concept of PWM.

To close this I would have to bet that most fires, BMS or no BMS are caused
by poor engineering, lack of fuses and just poor installation practices.
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[Peter Gabrielsson]

EV conversions have been burning to the ground far longer than there's
been BMSs around. Obviously a poorly implemented BMS can cause a fire,
just like a poorly implemented battery box, charger, wiring, heater,
DCDC, and whatever else that's capable of generating a little heat in
the wrong place.



> The Elithion site itself says 2 of the fires had Elithion BMS systems, Neil
> Young's LincVolt and Santa Rosa Junior College's Ford Focus EV conversion:
> http://liionbms.com/blog/2011/03/ev-fires-and-bmss/

LincVolt
"1) While the BMS was physically in the vehicle, it was not connected
to the charger, so it had no way of protecting the battery pack from
over-charge
2) The charger had never been adjusted for the battery voltage, and
therefore it kept on charging the pack past its nominal full voltage.

What we do know is that the LincVolt staff has very specifically said
“LincVolt suffered a disastrous accidental fire stemming from human
error”
"

> http://www.pressdemocrat.com/article/20110319/NEWS/110319406/1350?p=1&tc=pg&tc=ar
>
>
> Chevy Volt has a BMS. It's not certain if the Volt or the converted Suzuki
> Samurai or something else caused the fire (the Samurai I don't think had lithium
> batteries). The Volt later caught fire a 2nd time (but it was already fire
> damaged at that point).
> http://www.qualitychevy.com/2011-chevy-volt-news.html
> http://detroit.cbslocal.com/2011/04/16/garage-fire-starts-debate-are-batteries-in-electric-cars-safe/
>
> http://green.autoblog.com/2011/04/18/report-burnt-chevrolet-volt-mysteriously-catches-fire-again/

Well, GM claims the Chevy was exonerated and the Suzuki did not have a
BMS according to the owners website, in fact it had a bad boy charger
and NiMH batteries.

>
> A plug in Prius with a Hymotion system with a BMS:
> http://priuschat.com/forums/prius-hybrid-news/51283-prius-a123-battery-fire-report.html

There is a an actual investigation on this one, google and read it.
IIRC the fire was caused by a incorrectly assembled power connection
that heated adjacent cells to the point of ignition. If their BMS had
had adequate temperature sensing they may have been able to terminated
the discharge in time to prevent the fire.


> Reverend Gadget lost 7 conversions in a fire. He calls it "apparently an arson."
> While he does use  lithium batteries and BMSs, I don't know how many of these
> cars were lithium and which had BMSs. Can anyone help with that? The car of the
> 3rd link may or may not be one of the 7.
> http://www.electric-cars-are-for-girls.com/electric-car-kit.html
> http://www.revengeoftheelectriccar.com/_blog/The_Blog/post/Gadget%27s_New_World/
> http://www.garagejournal.com/forum/showthread.php?t=72411

So the mere presence of a BMS in a arson fire proves what?


> Three solar cars burned (implied they have lithium, doesn't say on BMS,  sounds
> like they were not Lithium Iron Phosphate chemistry):
> http://jcwinnie.biz/wordpress/?p=1788

The whole discussion on that website seems to suggest there was no BMS
on the solar cars, and at least one of the fires was attributed to a
short.

"I can really only recall one well built solar car that’s had a
battery fire in the past few years, and that was because of an
unfortunate short circuit."

"When batteries are put on a larger device (like, say, a car), there’s
more room for battery protection circuitry, and the batteries are
actively cooled. Taking into account the already very, very low
failure catastrophic failure rate found in laptop batteries, I’d say
that Lithium-based batteries would be perfectly safe to put into
cars."

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[Klaus]

I think both BMS and BMS free can work just fine IF properly executed.  And that's a very big IF.  So far as BMS related fires, I think there's a lot of ass covering going on, burring the facts, which is too bad.  A good BMS will allow operator ignorance at the expense of increase cost and complexity.  BMS free requires more knowledge and attention from the operator.  I'm in the the KISS, crank windows, manual locks and tachometer to help decide if I'm in the right gear crowd.  I also do not like shunt regulation on high current circuits.

[storm connors]

FWIW,
The bad boy charger was an experiment some time ago. The NiMH pack was
being charged with a Manzanita Micro charger, but with no monitoring
system. The battery pack had a working liquid cooling system, so I am
pretty sure the fire wasn't caused by batteries overheating. But no
cause for the fire has been determined.

On Wed, May 11, 2011 at 12:48 PM, Peter Gabrielsson
<[hidden email]> wrote:

> It's unfortunate.
>
> My guess would be that it was the NiMH in combination with bad boy
> charger, lack of ventilation and no monitoring system.
>
> Which reminds me, I need to improve the ventilation in my NiMH battery box......
>
>
>
> On Wed, May 11, 2011 at 8:08 AM, corbin dunn
> <[hidden email]> wrote:
>> Hi Peter, I have yet to see a fire that has been 100% for sure caused by a faulty BMS. Most EV car fires that I've seen haven't stated the exact cause of the fire. I also would like to see some references and backing proof for fires. I'm also worried about fires.
>>
>> One of the most recent EV fires in the news is Storm Connor's, which destroyed his home built Suzuki and Volt:
>>
>> http://stormselectric.blogspot.com/
>>
>> I hope Storm bounces back and builds another EV -- based on his website he seems like a really cool guy. I'm also interested in knowing what the cause of the fire was. It looks like it wasn't the Volt, and wasn't the Suzuki's charger, and he doesn't seem to have a BMS (based on looking at his website).
>>
>> corbin
>>
>>

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