I had a charging problem when I had a big block in my '88. I didn't do much with it at the time because I had a small block built to change too. Well, I have the same problem now that I have the small block in. I've got 2 batteries with a battery isolator. On my small block I have a 200 amp alt. Both batteries are grounded to the frame. One on each side of the frame rail. I have a wire (4 gauge) from one frame rail to the engine. These battery wires are 2 gauge to the frame rails. I also have a 4 gauge wire from the alt. to the isolator. When the truck is idling I have 12.24 volts on the terminal at the alt. The problem is when I drive around the volt gauge keeps dropping. Its like the batteries are not getting charged. I'm eliminating the alt. because this problem was doing the same thing with the alt. (stock alt.) on the big block. Any suggestions?? I don't know where to start. I'm thinking of eliminating the isolator and hooking both batteries in parallel. Could the batteries be going bad?? Please help.........I don't know what to do.....

 

are you using the same alternator on both engines or different alternators per engine?

 

I burned the lead off my 200AMP alternator in about 5 weeks. Then I replaced the lead, and shortly thereafter, (a couple days) the alternator started showing the same symptoms(at less than 6 weeks old) of a burnt-out diode plate. (This is where the alternator starts draining the battery after you shut the engine off.)

Just out of curiosity,who did you get the alternator from, and how long have you had it?

BTW, check to see if the lead from the alternator(you did upsize it, right?) is OK...

 

Hi is the belt slipping under a load?

 

Got my answer on another forum. When I took my original dash out and installed digital gauges I took the battery indicator circuit out also. Put my original dash back in and my charging problem is fixed..