# Help with batteries??



## nitrolux (May 8, 2014)

Hi All.

I am building an underwater video light unit. 
I have 2x light heads of an ROV which are 24-30v DC.

I want to build a canister to house the battery pack out of Delrin which I will machine to size.

Am I right in thinking Li-Ion is the way to go and using 3.7v cells? What AH should I get and what brand of battery?
Is there a way to work out what charger I need too??

I can mount the canister on my back beside my air cylinders so I can go pretty big.

Paul.


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## cy (May 8, 2014)

for a custom multi cell application like this .. LiFePO4 should be the top candidate for multiple reasons. LiFePO4 is inherently stable and will survive wild overcharge abuse without going into thermal runaway (explosion). LiFePO4's disadvantage of lower energy density goes away when larger AH cells are used. 

other advantages are 2,000+ cycles for LiFePO4 vs 500 cycles range for LiCo .. discharge for LiFePO4 is almost flat eliminating need for voltage regulation. 

what's the amp hour drain rate @ 24v? what runtimes are required?
2x 12v 20AH electric bike LiFePO4 batteries can be used in series. costs is about $125 each.

details can be found here: http://www.advrider.com/forums/showthread.php?t=757934
it's the world largest database for 12v LiFePO4 motorcycle batteries ..


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