From: "Hazen, Dwight L" <hazen indiana edu> Date: Thu, 9 Aug 2001 14:16:26 -0500 Sender: owner-elec-trak cosmos phy tufts edu You need a float charger "power supply" that is dead on for the voltage you set. 40.8 volts maintained over a long term should not gas the cells. I think this is too high. Manufacturers usually recommend 13.2V for a 12V battery. Ken