I know a lot of people parallel batteries and may get away with it much of the time. However you are charging into twice the load for which the charger is designed and at least your chargeing time is doubled.
If the batteries are not too differently charged to start with, you may be O.K. re: ballancing, but if the charges are different you can get some very high currents flowing while they ballance out, thus hot wires. You can get away with parallelling differently charged batteries when you jump car batteries because you have heavy leads between them and it doesn't last long. However wires used for charging are usually light thus could get hot over the many hours needed to ballance the batteries or charge them. I saw two battery systems on several boats which were charged with units intended for single batteries and the chargers usually died this is one of these issues where many people do it and so everybody seems to think it's O.K. I used to agree but experience with those expensive marine chargers tells me it's not. I believe marine alternators where the usual practice is to have two batteries on a boat, have seperate charging circuits for each battery. There is a switch that can connect either or both batteries to the load, and that's fine. tom Net-Tamer V 1.13 Beta - Registered
