My power supply is 2 1000 watt HP computer transformers for a total of 24 volts. I can charge off a 12 volt supply. I have the
http://www.progressiverc.com/icharger-306b.html charger
Specifications
• Maximum charge power capacity: 1000W (at >23V; 500W at 12V)
• Charge current range: 0.05-30.0A
•Discharge current range: 0.05-30.0A
• Input voltage range: 4.5-38V DC
•Maximum discharge power capacity: 80W
•Maximum regenerative discharge: 1000W
•Maximum external discharge power capacity: 1200W at 40V/30A
• Current drain for balancing: <500mA
• Balance accuracy: <10mV
• LiPo/LiIo/LiFe: 1-6 series (up to 12S LiFe in non-balanced mode)
•NiCd/NiMH battery cell count: 1-25 series
•Pb battery cell count: 1-18 series (2-36V)
•Battery setup memories: 10
• Intelligent temperature control: Yes
• PC Connectivity: USB port