Battery Vehicle Society

Hi All,

I'm after 40 Kokam 3.7V 40Ah cells for a CRF450 (dirt bike) conversion I'm working on. Just thought I'd check if anyone is interested in some sort of bulk buy to try and keep the costs down..?

Cheers,

Ed

I suggest you look again at the A123 20ah lifepo4 pouch cells as an alternative. They can be had for about $40-50 each inc shipping from a few firms now in china. Check on the endlessphere forum. I would say they are more resilient and longer cycle life and reasonable weight. They can certainly deliver the current, 600A is possible from a 20A cell.

I too would like the larger Kokam cells, 200~240AH rating.

Is there any cheap supplier to the EU/UK?
I do know of one supplier who's prices are beyond crazy.

You could order 3x 50V,60A packs from headway which will give you 150V @60A. 500A cont. and 750 surge.
They are around 4"x6" and 2' tall with the connectors on top out of the way. Will save you lots of assembly etc. The sellers ask $1,300 apiece but state they are packaged in 10's. Maybe some bike importer has some?

Thanks for the replies. I initally looked into A123 and it may work out a bit cheaper going by the 40-50 dollar cell price but I've always had trouble trying to source them and A123 themselves won't even respond. I was put onto Kokam directly by a UK BMS company called REAP which you've probably heard of. Kokam have been quick to respond but I don't have their quote details with me at the moment. I'll take a look at endless-sphere and also come back and post my quote details from Kokam when I'm back home in a couple of days.

My original quote from Kokam was as follows:

22 x SLPB100216216H(40Ah) bare cell US$2,926.00 (US$133.00 piece price)

Dangerous goods packaging and inspection fee US$200.00

Delivery costs from Korea to your warehouse by FedEx US$600.00

They're around 10-15% more expensive than the A123's but there's an improvement in energy density according to my checks which is important for my application.

If anyone's interested let me know otherwise I might have to bite the bullet and place an order...

The kokams have a higher energy density because they are lipo instead of lifepo4 like the 123 cells. Another difference is the voltage is about 3.7 volts per cell nominal, so you need to keep that in mind when selecting a bms, most of the ones availble are for lifepo4.

Thanks for the info, Greg! I'm planning on running a REAP BMS which is quite configurable. Think they've worked with Kokam quite a bit in the past as well.

Must tell you Ed,
I'd be wary of all those cost additions. Kokam will pack and charge you directly from China. The BMS sellers are middlemen. Unless the units you buy have any form of guarantee, I would avoid them.

If you look for the June 25th 2010 video, 12 mins in. Lots of good info
http://www.evtv.me/vidarch.html

Metric minds BMS was not required if you don't overvoltage or overcharge them. That will save you money.

Reap systems can put together a very good and reliable battery pack. If you can afford their price, you should get a bullet proof solution.