I you want it to last for 4 hours, then you need to find a 12V 8Amp-Hr Hour battery. For homebrew, I think Li-Ion batteries are out. You in the realm of sealed lead acid or gel cell batteries.
I you want it to last for 4 hours, then you need to find a 12V 8Amp-Hr Hour battery. For homebrew, I think Li-Ion batteries are out. You in the realm of sealed lead acid or gel cell batteries.