Battery questions

[Rimrock]

Originally Posted by Cat966c

How about if it was an 11.1 volt battery? I've found one on eBay that's pretty compact

That's the one to go for, that is the LiPo batteries with 3 cells, named '3S', mostly used these days for 12V setups. They are about 12.5 V fully charged, and one will typically recharge them when they have dropped to about 11.1V. A charger that is prepared for LiPo batteries is needed. And LiPo voltage alarm is needed, to hook up to the battery. If dropping the voltage bellow about 11V regulary, the lifetime of the battery will be relatively much reduced.