I didn't address the self-discharge on purpose. People will believe what they
want.
However, I had a pack of Calb 60Ah cells in my garage that I had drained to
bottom balance. I had forgotten about them and it had been over a year since I
did this. We were having the conversation about self discharge on this web site
and I got worried they were correct after I posted the article on here talking
about self discharge in Li Ion cells. So, I measure the voltage on all the
cells and found a couple that were down to 1.8 volts and then I thought they
were correct.
i took the cells and charged them. It was weird the voltage went allover the
place but I didn't give up. I discharged them and charged them and the first
time it had 25 Ah. the second time 45Ah and so I cycled them about 5 times and
every cell came up to full capacity. I know because I have the capacity sheet
from CALB and the all have serial numbers.
This inadvertent experiment confirmed the findings of the paper that I read.
Saying that self discharge is manifested in a temporary loss of capacity that
can be recovered by cycling the cells.
Now, not all the cells exhibited this behavior. There were three cells out of a
hundred that did this. The rest of them were fine.
From: Michael Ross <[email protected]>
To: paul dove <[email protected]>; Electric Vehicle Discussion List
<[email protected]>
Sent: Sunday, November 8, 2015 12:18 PM
Subject: Re: [EVDL] Rickard's EVTV let the smoke out> overcharged pack fire
blew up
I think the self discharge complaint is growing less all the time - with good
quality cells. But really large packs beg prudence. A golf cart packs, like
Jack sells which will be operated by non EV types, gets real benefit from his
bottom balancing and sealing. The little 10AH 48V packs used in light EVs and
bikes are a analogous - small, operated by the unwashed.
Whatever is done, a really dependable charge cut off function must be part of
any system.
Our ability to evaluate cell quality, and BMS quality and function is still
suspect (particularly for the cash strapped DIYer; as opposed to a large
company with real money to command action) so I expect this argument to
continue, and it should.
On Sun, Nov 8, 2015 at 1:03 PM, paul dove via EV <[email protected]> wrote:
There is no evidence thus far to support that theory.
It could have been a pack he uses to power his bench or one he was charging to
put in a car.
He does all sorts of crazy experiments like test the sag while pulling 1000
amps.
From the article it didn't sound like it was in a car.
From: Bill Dube via EV <[email protected]>
To: EVDL Administrator <[email protected]>; Electric Vehicle Discussion List
<[email protected]>
Sent: Sunday, November 8, 2015 11:51 AM
Subject: Re: [EVDL] Rickard's EVTV let the smoke out> overcharged pack fire
blew up
This fellow is the flag bearer for the small anti-BMS movement.
A pack fire (in this instance a pack explosion) was predictable and
unfortunately inevitable. I'm glad that no one was injured.
Pack fires do rarely occur even under ideal circumstances, ("The world
is an imperfect place, screws fall out") but this pack fire was simply a
matter of time, like a ticking bomb simply waiting to go off. As I
understand it, he has had less dramatic pack fires before.
It would be a positive outcome of this tragic incident if this were to
change a few minds in this minority anti-BMS crowd on the need for a
BMS. Unfortunately, the anti-BMS crowd doesn't understand, (or choose to
ignore the advice of the countless experts that /do/ understand,) that
variable self discharge exists in li-ion cells. It is a very real
problem in maintaining battery balance in a high-voltage battery pack.
This is why folks go through the trouble and expense of qualifying and
buying a BMS for each and every high-voltage li-ion battery pack.
Bill Dube'
On 11/8/2015 3:45 AM, EVDL Administrator via EV wrote:
> Not to cause controversy, but do I recall right that Jack Rickard is one of
> the guys who've said that lithium batteries without BMSes never catch fire?
> Or was that someone else?
>
> Certainly that's a claim I've heard, on the EVDL and elsewhere.
>
> David Roden - Akron, Ohio, USA
> EVDL Administrator
>
> = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
> EVDL Information: http://www.evdl.org/help/
> = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
> Note: mail sent to "evpost" and "etpost" addresses will not
> reach me. To send a private message, please obtain my
> email address from the webpage http://www.evdl.org/help/ .
> = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
>
>
> _______________________________________________
> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> http://lists.evdl.org/listinfo.cgi/ev-evdl.org
> Read EVAngel's EV News at http://evdl.org/evln/
> Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20151108/acefeedc/attachment.htm>
_______________________________________________
UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
http://lists.evdl.org/listinfo.cgi/ev-evdl.org
Read EVAngel's EV News at http://evdl.org/evln/
Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20151108/eeb6c260/attachment.htm>
_______________________________________________
UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
http://lists.evdl.org/listinfo.cgi/ev-evdl.org
Read EVAngel's EV News at http://evdl.org/evln/
Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
--
To invent, you need a good imagination and a pile of junk.Thomas A. Edison
A public-opinion poll is no substitute for thought.Warren Buffet
Michael E. Ross(919) 585-6737 Land(919) 576-0824 Google Phone(919) 600-2892 Cell
[email protected]
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20151108/14f02b41/attachment.htm>
_______________________________________________
UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
http://lists.evdl.org/listinfo.cgi/ev-evdl.org
Read EVAngel's EV News at http://evdl.org/evln/
Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
