So my battery won't hold a charge on my m42. About a week ago I changed the oil filter housing gasket and out everything back the tension on the alternator feels the same maybe just a tad more slack. Any idea what could cause it or the first thing to check? If I get my car jumped it will drive fine until I cut it off. Thanks in advance guys
Announcement
Collapse
No announcement yet.
Battery keeps getting drained
Collapse
X
-
How old is the battery? Some of the cheaper ones are only good for a few years. Anyway...
Check the static battery voltage.
If it's above/around, say, 12V: check the cranking voltage of the battery. If it drops below 9-10V during cranking your battery is shit, you're gonna have to replace it.
If it's below, say, 12V: you need to do a draw test to see what's killing your battery.
I'd do a draw test even if you replace the battery, just to be sure.
-
Battery keeps getting drained
Check the connections of your cluster, I read somewhere that if not connected the battery won't charge the car for some reason. Also do you have an aftermarket alarm? I've also read/ heard those can be a battery sucker if installed incorrectly or left on or somethingBMW tech
Umass Amherst
05 wrx sti
Comment
-
Was the entire alternator dead or just the voltage regulator? I had a similar condition a couple years ago, and it was regulator. Easy fix.Estoguy
1986 BMW 325, Alpenweiss ~ "Elsa"
Need a photographer, come visit my site: http://estoguy.wix.com/unique-perspectives
Comment
-
Originally posted by Stevoyayaya3 View PostLike on th si board? I bought a refurbished one from bma about a year ago
They only change the batteries and capacitors. There are about 15 transistors and voltage regulators which are responsible for the parasitic drain. If the batteries are new, the transistors are still 30 years old and will intermittently and rapidly switch on and off, even with the car off. This is what causes the parasitic drain.
If your drain is coming from the either fuse 10, 12 or 21, there is a good chance its the SI board still, super common.Owner - Bavarian Restoration
BMW and European Electronics Repair and Restoration
www.BavRest.com
My Feedback Thread
Our Facebook!
Follow our Instagram!
Comment
Comment