In case anyone is wondering what these are , lithium titanate oxide. 20C(poss.30) safe charge rate , up to 20,000 charge cycles. 1.9-2.4v nominal 3v max 1.75 critical low. 22 cells in series with each cell containing 3 in parallel. they get a max charge of 62v (2.8v ea). the low cut off is 42v (1.9v ea) meaning the inverter connected to them can never over charge or drain too low in operation and if one cell dies the other cells don't get overcharged, maxing @ 2.95v. They are fire proof, they don't explode, they can be drilled through, crushed and will not catch fire and will work down to -30deg c.