Battery Drain

[Bmwcrocop]

After 4-5 days when my car is sitting idle — I have a dead battery. There is a slow drain somewhere.

I disconnected the trunk light fixture/bulb and removed an old school Viper alarm. Strangely enough there is still a drain.

I also have an aftermarket radio and amplifier as well as a hella air horn.

Also, I noticed there is a ignition kill wire hooked up to my battery. When I remove the wire to the battery the car won’t start. I believe this is related to the alarm. Wires are still present and I have a picture. Not sure how to post pictures on here.

Thoughts?

Thank you in advance.
1997 BMW Z3 1.9l

[Bmwcrocop]

https://imgur.com/gallery/30Naj0J

[zellamay]

Have you measured the drain? There is always a small drain, but of course shouldn't affect the battery in just a few days. My problem, same symptoms as you describe, turned out to be a bad battery.

[Bmwcrocop]

I have replaced the battery 4x in the past. The Z3 is my second car and I rarely drive it.

I’ve got a dumb question— hot do I measure and look for drain?

[zellamay]

By pure luck, I just saw this thread on the E36 site: https://www.bimmerforums.com/forum/s...ectrical-issue Look at post #2 . Also, you have to disable the trunk light while testing, of course.

[Bmwcrocop]

Thank you. I will test and report back. Good looking out.

[solimans]

Lots on YouTube

Search “Find parasidic draw”


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[Tigershark48]

I cover my 2000 Z3 M during the Wisconsin winter months. I was tossing around whether I should buy a second battery tender for the Roadster or swap every other week with the one on my motorcyle. I ended up starting last winter with a full charge on each and measured drop on a week to week basis with no tender on either one. Turned out they both lost almost exactly 0.1V per week right up until Spring driving time. I gave each a top-off charge before the first startup with zero issues.

My point is the drop should be minimal and the OP definitely has either a parasitic draw somewhere in the wiring or a bad battery. My roadster has the factory alarm system and a continuously running analog clock.

[Randy Forbes]

I cover my 2000 Z3 M during the Wisconsin winter months. I was tossing around whether I should buy a second battery tender for the Roadster or swap every other week with the one on my motorcyle. I ended up starting last winter with a full charge on each and measured drop on a week to week basis with no tender on either one. Turned out they both lost almost exactly 0.1V per week right up until Spring driving time. I gave each a top-off charge before the first startup with zero issues.

My point is the drop should be minimal and the OP definitely has either a parasitic draw somewhere in the wiring or a bad battery. My roadster has the factory alarm system and a continuously running analog clock.

These are so cheap__cost-wise, not quality*__that there's no real reason to have to swap tenders every week.

https://www.homedepot.com/p/Schumach...E&gclsrc=aw.ds



* I have at least 6 or 7; 4 of them are on my own cars, and there's at least 2 more in the shop to put on customer's cars. The price has gone up (most of mine listed for $19.95) but they can still be found on sale for under $25.00. Some of them are 15-16 years old, and none of them have ever failed.