I've used 24 volt exclusivly for the last 3 years. I needed something strong enough to turn over my 45cc Homelite conversion. I use the Dynatron, and for juice, I use two of the sealed acid lead cells used in computer battery backups. They are small, light, and 7 Ah. Works great, and I can still use my 12 volt power panel.

Charge them every other week during heavy summer flying.