# [EVDL] Kokam Cells?



## EVDL List (Jul 27, 2007)

Bad form replying to my own question, I know.

I did find more technical information on the Kokam cells at: 
http://www.kokam.com/product/product_pdf/E-catalog_Kokam.pdf

(Most of the site is in Korean, but this .pdf is in English.)

Still looking for idea on cost and/or where to buy them.

Mike

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Mike Nickerson
Sent: Tuesday, December 08, 2009 6:55 PM
To: 'Electric Vehicle Discussion List'
Subject: [EVDL] Kokam Cells?

Hello everybody,

I was just looking in the EVAlbum at an RX-8 converted by Andrej Pecjak in
Europe. He used Kokam 200 Ah cells. I was wondering if these are readily
available in the US? I found information on them at houseofbatteries.com,
but haven't found anyone selling them to people like me yet.

Anyone with more information on them?

Mike

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## EVDL List (Jul 27, 2007)

I apologize for the repost. The way I asked this question before, it ended
up in the middle of the BMS discussion. I think I'm getting it right this
time.



Hello everybody,



I was just looking in the EVAlbum at an RX-8 converted by Andrej Pecjak in
Europe. He used Kokam 200 Ah cells. I was wondering if these are readily
available in the US? I found information on them at houseofbatteries.com,
but haven't found anyone selling them to people like me yet.



I did find technical information on the Kokam cells at: 

http://www.kokam.com/product/product_pdf/E-catalog_Kokam.pdf



(Most of the site is in Korean, but this .pdf is in English.)



Anyone have information on cost and/or where to buy them?



Mike



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## EVDL List (Jul 27, 2007)

Both John Wayland (White Zombie) and the ProEV (Electric Imp) guys are/where
(?) sponsored by Kokam
so an email to one of them may not be a bad idea ?
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## EVDL List (Jul 27, 2007)

You can order directly from Kokam America, they will drop ship from 
Korea. I did this (ordered 200 40Ah cells) and used to build trial
packs for my conversion: http://www.metricmind.com/audi/14-battery.htm

Watch out for one "feature" that ruined many of cells: the fused seams along
sides are *conductive* and there is voltage potential between edges of 
the cell and its terminals. I found it hard way when put aluminum around
thinking that plastic pouch the cell is in is insulator. Cells got
discharged to zero when touched aluminum sinks. When I asked Kokam why 
they "withhold" such important design information on their web site
(conductivity of the pouch) that resulted in ruining some cells in my 
case, they responded that basically one has to send them battery 
enclosure design for approval, else they are not responsible for such
"omissions".

So insulate battery edges if you want to use them in conductive 
container! I've learned quite a bit assembling and testing these
cells, and cutting open failed ones to see how they are made.

Victor

p.s. I do have NREL white paper with test results of Kokam cells
in GEM-like vehicle. They quit testing because cells could not
withstand cycling typical for driving mode. NREL's conclusion was that
the cells are not as tough as perceived (at least large ones, not
used in RC models world).





> Collin Kidder wrote:
> > Those look like interesting batteries. Quite a bit thinner than the
> > prismatic cells I've been using.
> >
> ...


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## EVDL List (Jul 27, 2007)

whats the pricing on the 40Ah and 70Ah cells?



> Victor Tikhonov <[email protected]> wrote:
> 
> > You can order directly from Kokam America, they will drop ship from
> > Korea. I did this (ordered 200 40Ah cells) and used to build trial
> ...


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## EVDL List (Jul 27, 2007)

Victor wrote - 
> I did this (ordered 200 40Ah cells) and used to build trial
> packs for my conversion: http://www.metricmind.com/audi/14-battery.htm

Very nice Victor. Seems that you have made a very nice package, good luck.

Rush
www.TEVA2.com

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## EVDL List (Jul 27, 2007)

I never had 70Ah ones. The 40Ah ones were about $215 each (for quantity 
of 200) by the time the hazardous class shipping from Korea and customs 
duty is paid for, this is 2007 prices.

Victor

Travis Gintz wrote:
> whats the pricing on the 40Ah and 70Ah cells?
> 
>


> Victor Tikhonov <[email protected]> wrote:
> >
> >> You can order directly from Kokam America, they will drop ship from
> >> Korea. I did this (ordered 200 40Ah cells) and used to build trial
> ...


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## EVDL List (Jul 27, 2007)

wow, spendy little things aren't they..... let us know how you like the
performance, I've heard good things.



> Victor Tikhonov <[email protected]> wrote:
> 
> > I never had 70Ah ones. The 40Ah ones were about $215 each (for quantity
> > of 200) by the time the hazardous class shipping from Korea and customs
> ...


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## EVDL List (Jul 27, 2007)

Wow! $43k worth of cells!

Sent from my iPhone



> Victor Tikhonov <[email protected]> wrote:
> 
> > I never had 70Ah ones. The 40Ah ones were about $215 each (for
> > quantity
> ...


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## EVDL List (Jul 27, 2007)

Yes, expensive. 1/3 were for me, 2/3 were ordered by someone else
I combined the purchase with. So my part was around $13k, that was fine 
with me.

They do perform well and stay alike, but fragile, tricky to make into
packs and once damaged won't perform well (I guess this applies to any 
cells). NOt as powerful as A123, but gravimetric energy contents, so you 
go farther for the same battery weight. The power/energy balance is 
about ideal for Kokam's - somewhere between A123 and Thundersky's.

I did limited testing on the bench (mostly BMS testing rather than cells 
themselves testing), but never had them installed in a vehicle, so
can't tell.

Because I lost quite a few due to this mistake in assembly, I have only 
~60 left out of 96 I bought, so not enough to make a pack, and I can't 
buy now more. Because competition
from many others now, Kokam has to lower prices so I can make up my loss
and get 36 more cells to replace NiMH pack in ACRX, then I'll have real 
world data. But Cliff Rassweiler from ProEV has lots of test data for
70Ah ones, so may share his experience. John Wayland will soon have test
data as well. Unilke these guys I don't get sponsorships as my vehicle 
is not as visible or promotional, so I got to pay for everything out of 
my pocket, therefore can't tell how soon I will have real test data 
available.

Victor

--
'91 ACRX - something different
'01 in-AUDI-ble - handsome car with 0.4MW AC drive - work in progress

Roger Heuckeroth wrote:
> Wow! $43k worth of cells!
> 
> Sent from my iPhone
> 
>


> Victor Tikhonov <[email protected]> wrote:
> >
> 
> 
> ...


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## EVDL List (Jul 27, 2007)

> Victor Tikhonov wrote:
> > They do perform well and stay alike, but fragile, tricky to make into
> > packs and once damaged won't perform well (I guess this applies to any
> 
> ...


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## EVDL List (Jul 27, 2007)

Maybe put som thin foam tap along the edges. That's what my cells com 
with.

Sent from my iPhone



> Rick Beebe <[email protected]> wrote:
> 
> > Victor Tikhonov wrote:
> >> They do perform well and stay alike, but fragile, tricky to make into
> ...


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