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Discussion Starter #1
This months PB has a small piece about making your own battery from DeWalt Nano Lithium Ion Poly-something batteries from a cordless drill which looked interesting. Found a few other threads on various forums, mostly radio controlled planes, about the same but nothing simple with motorbikes in mind.

Any of the electrical experts on here looked into this? It looks to be fairly straightforward to make up the cells into a suitable sized battery but I haven't found anything thus far about charging given that you I think you need a special charger??

It looked like an interesting project and the batteries have a very low self-discharge and of course end up weighing a fraction of the original...
 

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Basically you want a lithium ion charger that runs off vehicle 12V (so, 10-16V) that can address each cell individually. This is relatively tricky and unless you're doing it to a dirt bike, not really worth it for the weight saving IMO. And if you're doing it to a dirt bike which you don't use a lot, you might as well get a home charger and save weight by not putting a charge circuit on the bike.

That said, a good starting point is here. Bear in mind the cells you rip from the power pack probably aren't individually protected, so extra care must be taken.

Lithium poly has an unfortunate habit of exploding (normally due to abuse and improper charging techniques, but nonetheless having your battery pack explode could very easily write off the bike and you....), so I'd recommend either A123 or the more readily available LiMN chemistries which are safe- i.e, will not vent with flame no matter how much you abuse them.

A123 sources are a bit sketchy, but you can get LiMN from here, more details here. (He refers to them as IMR cells- you want either 18650 or 26500 size. 26500 is conventional 'C' cell size, 18650 is about 30% bigger in all directions as an AA cell.
 
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Thanks Jarl,

The charging aspect does sound like it would preclude the use of these type of cells on anything other than a race bike; thanks for the links though.

Cheers
David
 
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