Mystery Drain on the Battery - Please Help!

[bbarrington]

Hello,

I've searched the postings on this forum, but I can't find what I am looking for.

I've got an '88 Carrera and it has developed a mystery battery drain and so far I have not been able to determine the cause. I am measuring 680 milliamps through the battery with everything that I know about turned off. I have systematically pulled all the fuses one at a time (21 in the trunk and 3 in the engine compartment) and repeated the measurement - still 680 milliamps.

So does anyone out there have any suggestions of what I should do next? Any idea what could be draining the battery? I haven't added or modified anything electrical on the car in several months.

Someone mentioned to me that it is rare, but possible, that the alternator has failed and is the source of the drain on the system. Is this possible? If so, how would I test for this?

Thanks,
Bill

[Dpmulvan]

Try disconnecting the alternator?

[Barrpete]

The power windows have a relay that keeps power going to the windows after the ignition is shut off. It keeps the windows powered until the door is opened. When that relay goes bad it is a common cause of dead batteries. I'm not sure if it is fused or not, if not that might be your problem.

[Bob Kontak]

12V power to the alternator is huge. 12V only, but enough amperage to launch you into the neighbor's yard. Maybe pull the hefty red wire feed off at the starter solenoid with battery disconnected. Reconnect battery and then check draw.

I do remember reading about two months age about the power window relay in the 3.2's. It allows the windows to be closed after turning the key off but before the door is open. I think the door open switch shuts the relay down. That said, I have to think this system is fused so of no real value?

Aftermarket alarm with an in-line fuse somewhere? 680 seems too high for security monitoring system needs.

I am talking here - no experience - I believe the electrical connector to the ignition switch can be pulled off. That should eliminate juice from entering the ignition switch distribution system. Worth a try to isolate variables.

Also, pull the relays. I don't think there is a fuse on the front condenser motor (for example). Also a relay or two in the smuggler's box.

[Bob Kontak]

Originally Posted by Barrpete

When that relay goes bad it is a common cause of dead batteries. I'm not sure if it is fused or not, if not that might be your problem.

Timing overlap.

[darrin]

easy way to confirm the window relay issue -- can the OP operate his windows with the key out/door open? and/or does the op's dome light operate when the driver's door is opened / turn off with the driver's door? It's generally not the relay that's failing, but the door switch that triggers the relay to deactivate the window circuit.

[Barrpete]

darrin, you're right - its the door switch, not the relay that usually fails.

[bbarrington]

Thanks for the great suggestions, guys.

I've now eliminated the door switch possibility; the dome lights operate properly with door open/close and I cannot operate the windows with the door open. I also pulled the connector to the Viper and rechecked the current draw; still the same 680 milliamps.

I guess I'll start pulling relays next. I think I'm done for today at least - tired of messing with it with nothing to show.

[dan88911]

You find something here.
Batttey Drain Testing

[westcoast911]

Can anybody point out the location of the power window relay? I have repaired the door switches, but still have power to the windows at all times.

I have pulled the relay at the fuse panel and switched with another but that didn't help or change anything.

[bbarrington]

OP here - still no luck. I've pulled all 6 relays in the fuse box in the trunk and still in excess of 600 milliamps through the battery. Running out of ideas. I've blown the fuse in my multimeter, so I'm out of commission for the moment. Anyway, if anyone has any thoughts, I'm all ears.

Thanks.

[dan88911]

I am no expert on this and you may have already checked this.
The original owner of my car had battery problems the car was a garage queen.
The guy didn't wrench the car, his mechanic claimed it was the trunk lamp long story short I traced the problem to the door switch.However the battery would drain slowly drop off in a week or two a few volts.
I replaced it even tho it registered good. No more problem.

[timmy2]

Did you try what Bob suggested earlier about removing the cables at the starter?
Disconnect battery first and isolate the red and black cables before re-connecting.

[bbarrington]

Not yet. I guess that will be my next step. Dumb question though. If the draw goes down to an acceptable value, what exactly would that tell me? The solenoid is bad? Or what?

Thanks for the help.

[cdadaa]

bbarrington, what did you find out? I'm having the exact same issues and following this thread!

[bbarrington]

Well, I'm afraid this will not be much help, but I will let you know my status. Due to my work schedule and the fact that I needed new jack stands, the car sat in my garage for almost 2 weeks with the battery disconnected. This last Sat. I got underneath the car and disconnected the cable to the starter. I then measured the load through the system. It was essentially zero - definitely less than 50 milliamps. Then, just to double check, I reconnected the cable to the starter and did another measurement - essentially zero. So, I really have no idea what was causing the drain. All I can think of is that there is something on the car that causes a drain after shutting the car down, then dies off over time. Just a guess. I drove the car Sunday - checked the voltage on the battery before and after I left. It was higher upon return, so the charging system seems to be working. I also drove it yesterday to and from work with no issues. I plan to check the battery voltage sometime today.
So, in short, I have no idea what was causing the drain. I plan to monitor things for a while and will report back on this thread if I discover anything of interest. It's entirely possible that my original battery died a natural death, and that I just purchased a defective battery to replace it.
Sorry I can't be of more help.

[ganun]

Just to let you know there are more relays hidden and tucked behind the drivers side trunk hinge.
The said window relay is back in there labeled FENSTERHEBER, pull it and try your drain test, just to know, BTW the windows will still work.

[Homepro]

I chased a parasitic draw for nearly a year after we bought our '03 996 C2 with evidence that the problem had existed for a long time. I went through all the normal checks, light bulbs, pulling fuses, checking grounds, with no success. It still had a 320 ma draw. I had replaced the battery and had it load tested twice. I had removed the alternator and had it bench tested at the shop twice to no avail. I finally resorted to going over the entire vehicle with the IR thermometer and found the alternator warmer than the rest of the car. In order to access the positive wire connection to the alternator I had to remove it and found the alternator was drawing over 300 ma using a clamp on ammeter from Sears. Back at the alternator shop I demonstrated to the techs that my alternator was drawing 300 ma and a new one off the shelf was drawing zero. After replacing the regulator and rectifier the drain is gone and the battery holds it's charge. The main problem here resulted from the fact that the alternator shop equipment measures in amps and does not reflect a 1/3 amp draw.

[ischmitz]

Alternator diodes are semiconductor devices and can go partially bad. I'd replace the internal regular/diode pack and you should be fine