AWasserman

I am guilty of reading too quickly. Now I got it thx!

A

Alan

I do a lot of electrical work on my car - so I fitted a battery disconnect switch. I would not suggest it as the best idea for a battery drain issue - resolving the overcurrent cause or just regularly using a battery maintainer are better ideas there (no need for re-adaptation). I don't call it a "kill switch" because it will typically not stop a running car - however it is a great security and convenience feature.

See:
https://rennlist.com/forums/showthre...eferrerid=6055
https://rennlist.com/forums/showthre...eferrerid=6055
https://rennlist.com/forums/showthre...eferrerid=6055
https://rennlist.com/forums/showthre...eferrerid=6055

AWasserman

Latest news:

I disconnected the hatch switch so I could open it without changing the state of the system.
I left the car for 24 hrs and then tested the voltage and the current. It was a little over 12 volts at the battery terminals, and 0 amps current as measured at the battery ground strap.
I started the car: started just fine ran it for les than 5 minutes turned it off.
Left it for another 24 hours repeated the tests Voltage now a little under 12 volts (makes sense because I started the car the day before without letting it run more then a few minutes), 0 amps.

I will continue my experiments. Sooner or later I will catch the gremlin. And thank for all of your tips, they have made trouble shooting much easier and better.

AZW

dr bob

A healthy battery should sit with a settled voltage of 12.6. Fully "Smart-Charge" the battery, and verify that the voltage stays up to that level even after a week of sitting.

The normal parasitic loss of the car, sitting with doors unlocked and key out of the ignition, is about 35 milliamps. That's thirty-five thousandths of one amp, so needs a meter setting that reads that low.

Several of the possible conditions that cause a bigger number than that will disappear when power is interrupted. To find those, you'll want to have the meter set up for measurement prior to actually disconnecting the main connection. A set of test leads with alligator clips is a must. Connect one lead to chassis ground away from the ground strap, and the other to the ground strap itself or to the negative terminal on the battery. When you lift the chassis end of the ground strap, your meter will continue to be in the current flow path and give you a valid reading. The primary meter I use has a 10-amp range, plus lower ranges that use a different test lead connection. Read the directions for your meter to make sure you are properly connected. The 10A range on mine includes a separate fuse too. If you overcurrent the meter and blow a fuse, you'll get false zero readings and may not know it.

A few years ago I found a cute little DC clamp-on ammeter for doing some of these measurements without opening the tested circuit. For the lower ranges, it's so sensitive that I need to zero out the effects of the earth's magnetic field prior to an actual measurement. I can use it to chase losses wherever I can get a clean grab around a wire, but it really deserves a follow-up with a quality "wired" meter to validate a milliamps reading.

Billu

Hmmm, disconnected the hatch and the problem went away.....
Maybe....

AWasserman

dr bob: Thx for the further info!
Billu: actually I disconnect the hatch switch a long time ago, so that is not it

AZW

Alan

Well the 0 Amps is not plausible - It means - as Dr Bob noted - that you need a more accurate measurement method - we are looking for milliamps here. I suspect you still have something else going on that is temporarily in hiatus.

Could be interior lights (even just door end lights if you have all others switched off), could be the alarm, could be the central locking, window controller, fan controller. I doubt it is as simple as you currently think. I'd invest to be able to measure it properly.

Alan

ddire333

Had similar issue, was the amp (uk car so wrong side for you), but if the ticking is constant its actually a huge help to finding, pull each fuse, then relays, one at a time - if the noise stops you have narrowed down to the circuit with the issue for more detailed testing.

wigwampro

For what it’s worth, on my 86 S2 Euro, I traced a parasitic drain of ~4 amps to my rear hatch switch and aftermarket alarm system. Unplugged both and now I’m at 35 milliamps. You can use a tennis ball to “close” the front door switches while testing the CE panel and measuring parasitic drains from battery using a multimeter. I also had clicking that was from the aftermarket alarm system. In order to turn the clicking (and alarm) off, I had to hit an aftermarket switch/button in my glove box. Once the alarm was removed by simply removing an in-line fuse, the ticking and the battery drain went away.

AWasserman

All,

I am going hard core binary elimination now.

• I have ordered a analog ammeter with a 0 to 200 ma range.I figure I ought to get a nice clear reading off of that. When I get it, I will wire it up between the ground strap and the chassis as per Dr. Bob's advice. While I am waiting for it to arrive I will set up the experiment.
• I have two batteries in the trunk, one that I drive on, and one freshly charged (on a Noco battery conditioner) as a control. The control is at 12.9 V, the test subject is at 12.5 V after a jump start (it was at 9.5V). and a nice hour long drive.
• I parked the car and disconnected the ground strap.
• I will check at regular intervals while the car is parked (every 8-12 hrs and see if they are both holding their charge.Obviously, if the test subject is not holding its charge while disconnected I will swap in the control.
• Then I will drive it, testing battery voltage before and after the drive to make sure that the alternator is doing its job well.
• Then I will park it with the ammeter completing the circuit at the ground strap and visible from the hatch window with all doors locked.

I will report back after doing all this.

dire, I would be interested in hearing more about your amp problem. You do mean the audio power amp right? I ask because I am in fact having audio problems that *might* be the amp (or it might be the head). Half the time the sound system plays at roughly half its normal volume, and the there half of the time it is normal. I have not found a pattern but I will look for one now...

Thanks all,
Adam