# [EVDL] Lithium concerns



## EVDL List (Jul 27, 2007)

I have a brand new pack of 100 100ah Calb cells.
I am using the Lithiumate Pro BMS.
The cells have never been below 3.1V or above 3.6V.
They only have a few hundred miles on them.
When I take the lid off the pack I smell what must be electrolyte.
This can't be good.
Do I have a cell or cells with a bad vent seal or cracked case?
If that is the case, it will be very hard to find out which cell it is.
I'm pretty sure the cells aren't supposed to vent under normal use.

Thanks for any comments, Al

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## EVDL List (Jul 27, 2007)

Sometimes the seal on the pole vents under pressure. Big issue is not
the smell but having it sucking humid air back in after the pressure
releases.

You can see the venting when logging the voltage behavior of the cell.
You need to have quite accurate system for good diagnosis but this is
why high-end BMS can detect most of the failure mechanisms before
anything happens. You'll have more than 10.000 miles left on the
venting cell still. No worries.

There must be a mechanical way to detect the venting cell. Hmm..
Smells like a cheap tester business here.

For now.. install a small ventilation device (computer blower, etc.)
to get the vapors out. You'll get head aches if you have to smell it
for too long periods of time.

-akkuJukka


http://www.google.com/profiles/jarviju#about


2012/7/11 Al <[email protected]>:
> I have a brand new pack of 100 100ah Calb cells.
> I am using the Lithiumate Pro BMS.
> The cells have never been below 3.1V or above 3.6V.
> They only have a few hundred miles on them.
> When I take the lid off the pack I smell what must be electrolyte.
> This can't be good.
> Do I have a cell or cells with a bad vent seal or cracked case?
> If that is the case, it will be very hard to find out which cell it is.
> I'm pretty sure the cells aren't supposed to vent under normal use.
>
> Thanks for any comments, Al
>
> _______________________________________________
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## EVDL List (Jul 27, 2007)

How long do you keep cells at 3.6V?
It may sound strange, but you may be overcharging
the cells by keeping them at 3.6V, because the
charging protocol is to charge them at a certain
current, for example 0.1C (which would be 10A in your case) 
but I forget how much it exactly is - see the manufacturer
spec or search the archives, and as soon as the cell reaches
the 3.6V level you should stop charging it.
By keeping it at 3.6 a BMS will over-charge the cell.
It has been contemplated that you may want to lower the
BMS threshold voltage to around 3.45V and possibly you
are not overcharging them when you keep cells at that level.

I am not a Li specialist nor have I played a battery engineer
in a commercial, so do you own due diligence...

For me, the smell tells that at least some of the cells are
being overcharged, so I suggest to lower the (BMS) voltage
or the time they are at the 3.6V level as short as possible.

Search the archives for the full discussion and/or consult
a Li battery specialist.

Success,

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water XoIP: +31877841130
Tel: +1 408 383 7626 Tel: +91 (040)23117400 x203 

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Al
Sent: Tuesday, July 10, 2012 8:58 PM
To: Electric Vehicle Discussion List
Subject: [EVDL] Lithium concerns

I have a brand new pack of 100 100ah Calb cells.
I am using the Lithiumate Pro BMS.
The cells have never been below 3.1V or above 3.6V.
They only have a few hundred miles on them.
When I take the lid off the pack I smell what must be electrolyte.
This can't be good.
Do I have a cell or cells with a bad vent seal or cracked case?
If that is the case, it will be very hard to find out which cell it is.
I'm pretty sure the cells aren't supposed to vent under normal use.

Thanks for any comments, Al

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## EVDL List (Jul 27, 2007)

> Cor van de Water wrote:
> 
> > It may sound strange, but you may be overcharging
> > the cells by keeping them at 3.6V, because the
> ...


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## EVDL List (Jul 27, 2007)

Jack Rickard's chart: http://23.21.184.60/evtv-word-press/wp-content/upload=
s/2012/07/CAchargecurve.jpgshows going to 3.6V put 187 Ahr into a 180 Ahr c=
ell, and that continuing to hold 3.6V put in an addition 1.6% capacity (up =
to 190 Ahr). So yes, stopping at 3.6V does slightly undercharge, but not by=
much and that could be safer than trying to run right to the limit (Lithiu=
m is less tolerant of overcharge than lead).



________________________________
From: Roger Stockton <[email protected]>
To: Electric Vehicle Discussion List <[email protected]> =

Sent: Wednesday, July 11, 2012 9:06 AM
Subject: Re: [EVDL] Lithium concerns
=



> Cor van de Water wrote:
> 
> > It may sound strange, but you may be overcharging
> > the cells by keeping them at 3.6V, because the
> ...


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## EVDL List (Jul 27, 2007)

Well... Hysteresis is there and you can maintain the CV phase forever.
It will keep the cell at full.

We did single cell charger programs for large prismatic cells with
CC/CV curve in a way that when the LFP cell reaches 4.3V and current
less then 2A the charger goes to 'wait' -mode. Charger waits for few
minutes or longer (depends on the selected program) and sets the
voltage at the terminals as CV point. I_max was set to 1A. Then it
kept cell fully charged until it was removed from the charging system.
This is the way how we initiated cells after long transport.
Systematically all cells. (There were failsafes too to detect bad
cells)

Doing this (not exactly as described above but close) after few years
of operation it refreshens the cell. Regains capacity.

You can use the LiFePO4 cells nearly all the ways you can and they'll
provide the lifetime of the conversion.

-akkuJukka

http://www.google.com/profiles/jarviju#about


2012/7/11 David Dymaxion <[email protected]>:
> Jack Rickard's chart: http://23.21.184.60/evtv-word-press/wp-content/uploads/2012/07/CAchargecurve.jpgshows going to 3.6V put 187 Ahr into a 180 Ahr cell, and that continuing to hold 3.6V put in an addition 1.6% capacity (up to 190 Ahr). So yes, stopping at 3.6V does slightly undercharge, but not by much and that could be safer than trying to run right to the limit (Lithium is less tolerant of overcharge than lead).
>
>
>
> ________________________________
> From: Roger Stockton <[email protected]>
> To: Electric Vehicle Discussion List <[email protected]>
> Sent: Wednesday, July 11, 2012 9:06 AM
> Subject: Re: [EVDL] Lithium concerns
>


> > Cor van de Water wrote:
> >
> >> It may sound strange, but you may be overcharging
> >> the cells by keeping them at 3.6V, because the
> ...


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## EVDL List (Jul 27, 2007)

> David Dymaxion wrote:
> 
> > Jack Rickard's chart: <http://23.21.184.60/evtv-word-press/wp-
> > content/uploads/2012/07/CAchargecurve.jpg> shows going to 3.6V put 187 Ahr
> ...


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## EVDL List (Jul 27, 2007)

> Roger Stockton <[email protected]> wrote:
> > a typical charge termination criteria might be 1-2% of the rated capacity: 1.8-3.6A.
> 
> Roger,
> ...


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## EVDL List (Jul 27, 2007)

I just opened up several boxes of CA180 cells and the tested capacity from 
CALB was showing from 181Ah to 198Ah. This is a small sample but I was 
surprised to see this much variation in capacity. 

The CA100 cells run fairly close to the SE100 between 108Ah to 112Ah

Don Blazer


In a message dated 7/11/2012 9:11:55 P.M. Pacific Daylight Time, 
[email protected] writes:

Information for the specific cell tested in this plot, CA180FI, is not 
readily available online, however, it does appear that the discharge capacity 
should be quite near to 200Ah (dependant upon discharge rate, of course), so 
it is quite possible that even the 190Ah returned in Jack's test did not 
fully recharge the cell.

Unfortunately, without knowing the discharge Ah before and after this 
charge cycle, it really isn't possible to determine just how near to fully 
charged the cell was when the charge was terminated.

Cheers,

Roger.

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## EVDL List (Jul 27, 2007)

> David Nelson wrote:
> 
> > You've made a similar statement before but the printed documentation
> > which came with my TS cells says 0.01-0.05C as the termination
> ...


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