A household name with all DIYers of battery. The world is a better place because of these good folks who are actually doing good instead of talking about it. Probably a good idea to polish up on Physics regarding charged particles, electromagnetic phenomenon, and power/energy to re-acquaint yourself with Volts, Watts, Ohms, Amps, etc.
Ian also has a couple of LiFePo4 batteries at his warehouse in Utah with very competitive pricing.
Chinese battery company apparently with warehouses in California and Georgia selling server rack 48v batteries at a very competitive price.