Hopefully someone can help point me in the right direction.

88 Firebird 305 TBI.

Recently replaced battery, starter and alternator. The problem I am having is that the charging system is boiling the battery unless I unplug the cooling fan (*edit: also need to pull the Heater/AC fuse). Problem with that is if I unplug that, the system doesnt charge at all. I run on just the battery.

Anyone point me in the right direction of what to look at/for? This is driving me nuts. And the retailer where i got the battery is really not liking handing over so many batteries under warranty

 

The heater fuse also supplies exitation voltage to the alternator, so it's normal that it doesn't charge without it. There may be two red wires from your alternator, are they connected together? The thinner of these is a voltage sense wire, that if connected to something with a lower voltage than the battery/ alternator, would lead to an overvoltage condition. Other than that it sounds like the regulator in the alternator is shot. Get it tested, or buy a digital multimeter to measure some voltages if we are to be able to be of any help.

 

Thanks Fullsizewagon. I pulled the alternator again and had it retest. Tested good. Decided to check all the grounds again and have fixed the problem now. I think. The ground to the fended and the block were extremely rusty. Took them off and cleaned them. Now seems to be charging just fine. Although time will tell for sure.