Re: Hey digital console users don't forget your UPS
EVolve Electrics (www.Evolve Electrics.com) would be a source for 28 volt batteries.
I just replaced the AGM SLA batteries in my electric bike with two 8 packs of GBS 40 amp hour LiFePO4 batteries.
Nominally they are 24 volts (four would be "12v", 3.3v per cell), but the GBS charger (available in 12, 24, 36, &48v) takes them to 29 volts, 3.625 volts per cell.
A normal "smart" 12V charger won't harm a four pack of LiFePO4 batteries, as it won't take them to full charge.
Actually, 3.8v per cell is closer to full charge, but since some cells may be slightly lower while others receive slightly higher voltage in a pack it is not advisable to use that high a voltage for multiples without a battery management system, as LiFePO4 will be permanently damaged by taking them too high or too low in voltage.
LiFePO4 batteries are far more expensive and take more care than SLA, but weigh only a fraction of the weight for power delivered, the pair of 40 AH batteries weigh in at about 52 compared to 72 pounds for the 16 AH AGM SLA batteries. And the SLA really can only be discharged to about 55%, while the LiFePO4 can go to 80% discharge with no problems, so the weight is about 25% for power delivered.
The battery packs in the pictures below could run 10 amps of FOH gear for over 3 hours!
