I have recently gone over to LiPo batteries too. for Cherub and Gabriel, (the ones previously suggested) and I have to say they do work well I use a large two channel charger,
http://hobbyking.com/hobbyking/store...ger_800W_.html
It will charge the two packs at 15A each but dose require a power supply that can deliver 75A to power it!
I called it Brutus the battery charger.
I do have to say these batteries must be handled with extreme care, as the potential power stored, and chemicals used in them, means they can present a real hazard to yours and others health.
But they are good.