We have a 1973 with a 302. The ALT light came on so we put in a new alternator. Since then, the battery will not hold a charge, even to the extent of it discharging the battery. We have removed and tested the alternator several times, replaced the regulator, checked all the wiring multiple times, put in a new battery, still nothing. Puzzled!! Any help is greatly appreciated.

 

More info: It jump starts and runs fine until the battery gets down to about 6-8 volts (2-3 mins). During this time, with volt meter on the battery it seems like it is discharging rather than charging, reflecting the voltage of the battery. We've checked the wiring several times thinking that we wired it backwards but it is all correct. What are we missing???? Any help is welcomed

Before I changed the voltage regulator, we tried the "+" battery cable removal technique and the car immediately died. Since then, the alternator has been rechecked and a new regulator installed.

 

First off I recommend charging the battery all the way up with a charger...

My guess is that one of the wires might be broken inside.

At the regulator, one wire should be hot all the time, and another should be hot with the key on. Use a test light or multi-meter to check this out, this will give you a starting point for troubleshooting.

Also, the ground wire for the regulator is very important.

 

Thanks JMD! We actually found 2 problems: The first is what you said, a broken wire inside the insulation and the second was that the new regulator was bad. All fixed and working better than ever.