Posted by David Sherman on Monday, September 20, 2004 at 5:50PM :
In Reply to: 24v system - two batteries DEAD posted by Brad Zevenbergen on Monday, September 20, 2004 at 2:25PM :
Has it been sitting since last fall? If so, no wonder the batteries are dead. I find that every vehicle draws current from the batteries even when "everything" is off. If I disconnect the ground cable, a good battery will stay charged from fall till spring, even sitting out in freezing weather most of the time. In two-battery systems, one battery failing will cause the other one to get over- or under-charged. If it's not been going on for too long, an under-changed battery can be charged on a battery charger, and an over-charged one can just have the cells topped off with distilled water. I'm sure it's best to replace both batteries at once and use identical types, but on my rigs that use dual 6TLs, I just replace whichever one is dead, making sure both batteries are thoroughly charged on a battery charger before using them. I check the voltage of each battery periodically and if they don't agree very well, I figure out which one is bad and replace it before I ruin the other one too. If you have anything connected to the midpoint of the two batteries, like any 12 volt accessories, this will cause endless battery trouble. When I bought that M211 brush fire truck, the fire chief told me the thing just kept eating batteries -- they'd replaced everything and the batteries just kept going bad. Come to find out they had the radio and emergency light hooked to the midpoint of the batteries. I put a couple of my used 6TLs in it and it's been fine.