Freaky Electrical Problems Need Serious Help

[kenny21]

HI
I have a 68 Stang with a 289. Just recently the battery went dead so I charged it and everything worked fine for about 6 hours. Then all of a sudden the alternator started overcharging the battery at 18 volts. Now here's the weird part, If I'm touching the brake it shows a dead battery, one day I had the car running turned on my heater and started to put up my top and the car died. But when it fires up it overcharges. Everything to do with the charging system is new, battery, regulator, alternator and my starter solenoid. I know for sure i have a short but I haven't a clue where it could be. I've tested most of the wires in the engine compartment and inside the car, but am totally lost. Any good ideas

 

[tos]

I would say its your voltage regulator or possibly the alternator itself. Normally I would say its your alternator from the symptoms you gave. The system works like this. Your battery initially supplies the voltage to charge the coil for starting. Once the engine starts the solenoid (also could be here) switches to allow the alternator to now supply the charge to the coil. If the alternator does not take over then the engine gets its juice to charge the coil from the battery itself. If thats the case then your battery is working overtime charging the coil. Now add another drain on the battery such as putting the top up and now you've taken that power to the coil away cause the battery cant handle that kind of demand. Hope that makes since. I dont think you have a short. I would first check to see if your solenoid is wired right then check its operation. replace it cause they are cheap. Next make sure the alternator is wired right and check its operation. Next check the voltage regulator. Hope this helps.