As well as charging tempco, ambient T is significant for longevity - Trojan claims (for their deep-cycle lead-acid batteries) that the longevity & charge capacity lines cross @ 77=BA F; lower T lengthens life, at the expense of capacity. You did'nt mention the depth-of-discharge you anticipate... --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .