My company sells Industrial battery chargers from 2 to 20 Amps for both 12 and 24 V applications, for mainly large diesel and gas engined generator sets and we also supply the generator control systems. There are generally two or more sorts of chargers being used. (A) The Boost and Trickle charger variety - to be avoided at all costs, as even when left in trickle mode over a period of time, will cause the battery to dry/boil out and it is then U/S. (B) The Constant Potential type - The type to B/C to use and similar to a battery conditioner. When charging, the constant potential battery charger will provide high current and voltage to bring the float level of the battery up to nearly fully charged state. Once it gets near there, the current automatically reduces to a very small level. Once the voltage of the battery reach full charge of say 13.4 volts, the two voltages are equal and current does not flow. So although connected, it is not charging. If the battery voltage drops due to internal losses, then the charger brings it back to full charge slowly and stops charging. On large generators when you have very expensive starting batteries for 1500 - 2000 Bhp engines in a Hospital or Data Centre, we double up on everything, as the engine has to start. These chargers are left on 24/7 - year in and year out. I have a Banner charger for the 7 and it does a good job and is switched on all year round and I am still on the same battery - so far after three years. The CTEK is also good. Both of these are battery conditioners but work on the C/P principle. I would avoid using a standard battery or trickle charger for any length of time. Piers