From: "Dave Nadler"

Second the max voltage warning. ILEC has already seen some fried
avionics from customers experimenting with these things...

This is just one more reason to use LiFe instead of LiPo or LiIo. A
fully charged A123 LiFe pack delivers 14,4V (3,6V x 4), same as SLA.
20 A123 cells in 4s/5p configuration have almost the same dimensions
as a 12V/7Ah SLA but offer slightly more voltage, 11,5Ah and power to
start a car at 70% of the SLAs weight. And you can fast charge the
pack in 15 minutes if your charger can deliver 50 amps :-)

Michael