Technical 64 Impala Battery Drain

Hi there, I finally joined after lurking for many years. I have a 64 Impala that has a battery that is slowly draining. We recently had work done on the car and the battery was not draining before the work was done.

When it was in the shop the gas tank (and sending unit), the voltage regulator, and the parking brake switch were replaced. The motor was out and cleaned up a bit as well.

When I picked it up the tail lights were flickering and those were quickly fixed with the loose ground at the trunk lid light.

I disconnected the e-brake switch but the battery still drains.

I decided to jump in with a test light (The car is at my parents house and my Dad's meter wasn't working). I may be headed down the wrong path on my troubleshooting but I did find that the "Tail" fuse had power across it with the lights off, doors closed, trunk closed, etc. I also disconnected the trunk lid wiring connector and removed the other 2 tail lights. After that the "Tail" fuse still had power. Not sure if this is contributing to the battery drain or not and I ran out of time before tracing wire by wire with the diagram. I'm assuming that crossed wires would short and blow the fuse. The fuse block in the attached photo is not the actual one. I found that on the interwebs. Ours is not corroded.

A few questions:
Where is the best place to start troubleshooting a battery drain on this car?

Could the voltage regulator being replaced lead to this (wires not hooked up correctly, etc)?

Should the "Tail" fuse have power with nothing on the car appearing to be on?

Any suggestions are appreciated.

 

The voltage regulator is a likely suspect. I have a 71 chevy truck that has been a 20 year project.I recently got it on the road,and had a parasitic drain. I changed several alternators,a couple of used batterys,then took the new ac delco alternator to the local electrical guy,the alternator was fine,but he advised me that the regulator could drain the battery if not working properly.it was a new sealed ac delco regulator,so I dug through my used parts and found one.I changed the regulator and haven't had a dead battery in weeks.

 

Before guessing- Start pulling fuses= look for the draw if your able to. A meter is of most importance here in your diagnoses. We don't need to guess the problem, we need to solve it.

 

I believe the taillight fuse should be hot always, it feeds the switch so your lights can be on anytime.

 

Disconnect the positive cable from the battery, then hook a test light between the battery and the battery cable you just unhooked in series and it should light up if there is a drain on the system. Disconnect fuses one at a time and when the light goes out, that is the circuit you should investigate.

 

i had an olds that ran the battery down every couple of days. turns out the trunk light was the culprit.

 

Trunk lights, hood lights and glove box lights have caused many battery drain problems.

 

You can use a volt meter set up the same way. You will want to disconnect anything that runs when ignition is off. Clocks will show up but drain very little. Buzzer with key in the ignition etc. And then start disconnecting the fuses. Also while disconnecting the fuses put a piece of tape over your dome light switch so that circuit doesn’t show up(door open)


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I'd start by setting the meter for 10A (or higher), pull the fuses one by one and measure between the fuse connectors. If there is anything in that circuit drawing power it will show up on the meter.

 

Thanks everyone for the replies. Having the tail circuit active makes sense now that you mention that.

I was able to check the voltage regulator and when I set up the test light between the disconnected negative battery cable and the battery the light is on. When I disconnect the VR the light goes off. The new multi-meter should arrive Tuesday.

I'd assume this means that the VR is the culprit. This is a brand new unit. Is it really likely that a brand new unit is bad? Could a wire or two be swapped (I didn't have time to check to the wiring diagram).

The green wire in the photo comes directly from the battery to the relay. Disconnecting that green wire or the clip to the VR turns off the test light.

 

If your battery was not draining prior to service why did you replace the regulator?

 

As well as dome light/doorjamb circuits.

 

Is this a generator electrical system? They generally use an electromechanical regulator, that use vibrating points for voltage, current, and cutout. The latter are prone to sticking, especially if not cleaned periodically. This will cause the battery to backfeed into the generator field windings with the engine off. It will try to motor and may even turn over the engine. Sometimes you'll see dents on the top of a generator regulator cover, "percussive maintenance" in the field, to remedy this.