Auto battery drainage,what can I do ?

have a 1965 Chevy truck with a 283 V8. The other day the truck quit on me as I was driving and would not crank back up due to a dead battery. It seemed like a classic alternator problem so I installed a new one. The battery was completely drained and older so I went ahead and replaced it as well. I also replaced the voltage regulator and wiring harnesses in that region due to their poor condition.

My problem is, the battery continues to rapidly drain (within an hour or so) even when parked and no key in the ignition. If I crank the motor and pull the positive off of the battery, the motor dies. I have replaced and tested the alternator and regulator twice to verify their condition.


If the truck won't idle with the battery disconnected, the alternator is not putting out, so that is problem number 1.

If a fully charged battery goes dead when the truck is parked, even though nothing is left on, that is problem number 2.

Attack problem number 2 first, because something must be drawing lot of current and you could wind up with a fire!

With the battery fully charged, put the battery in the truck and disconnect one of the battery cables from the battery. Do you see a spark when you tap the cable end on the battery post? If you do, you KNOW something is on, even though you don't think it is. Start pulling fuses and checking things for feeling hot until you eliminate the spark.

If you don't have a volt-ammeter, that is the best you can do. If you CAN get a meter, connected it on the highest amperage scale in series with the disconnected battery cable, so as to complete the connection through the ammeter - this will tell you how much current is being drained. Since your battery goes down in only a short while, it must be a massive drain, so you are going to need an ammeter that can read up to 30 amperes or so to avoid burning out the meter.

When you get this all set up, just start pulling fuses and disconnecting wires until you find out where the power is being consumed. Likely candidates are things that draw a lot of current normally, like the headlights (but you'd have noticed that, of course) the horns or horn relay, (and you'd hear them, unless the horn doesn't sound off anymore), the alternator itself (it will feel hot if it's got a failed diode, allowing it to drain the battery), or some accessory that I can only guess at. Power seats are famous for this, but I doubt a 65 Chevy PU has those. The AC clutch, if it has AC is a possibility. If you've got any aftermarket stereo, winch, trailer brakes or hookup, or lighting devices, disconnect them to see if the problem clears. You'll just have to play detective and disconnect things until it goes away.

As for problem number 1, since you say you know the alternator and the regulator are OK, the problem has to be in the connections from the alternator back to the battery. I'd check the bulkhead connector in the firewall, the connections on your ammeter in the dash (if your model has an ammeter), the connection from the ignition switch to the regulator, the grounding of the alternator itself to the engine block etc. If you can't find anything wrong with the wiring, take both items back to the store and ask them to test them again - I can't work any magic for you, it's just detective work!