95' 318i battery dying overnight

[88mm]

My battery has been giving me problems for a few months now. On the weekends if I don't run the car it won't start come monday morning. But now it seems as though the battery will die after one night of sitting. I did a parasitic draw test on it and it was only drawing about 30 mA. I've got a couple of fuses that are blown in the fuse box. Don't know if that'll affect anything.

The battery is about a year old. I hear some sort of buzzing, almost electrical buzzing sound from behind the radio and climate control panel when the car is off. My battery measures 14v when the car is running. My connections are tight and super clean at the battery itself. Other than that there's not really any visible/audible symptoms that might cause the issue. Bad battery maybe?

Has anyone ever encountered a problem like this before?

Any feedback is greatly appreciated. Thank you.

[NERO2K]

Got the same problem, i'd replace your fuses first, then if you have an aftermarket radio, make sure you turn it off, as well as check and maker sure your door lights are going off when you shut the doors, if all else fails, might be a bad battery, or connections.

[spyderg0d]

Ive had the same problem.. Used several different good batteries and they still die. I have a parasitic loss of less than .01.. Still dies... The only thing i can imagine is the ground strap is cruddy and not allowing amps through (but voltage is). Or, the altinator is putting out volts and not enough amps to charge the battery. ..
I did find my parasitis loss to be in either the cluster or the obc.. Maybe that should be your next step? Find your parasitic loss.

[shogun]

Maximum closed current by vehicle, make a closed current test

E31 50mA
E32 50mA
E34 40mA
E36 30mA
E38 50mA
E39 40mA
E46 40mA
E52 50mA
E53 40mA
Z3 30mA

Performing Closed Current Draw Test
• Select proper measuring device (DISplus, MoDic or DVOM), Remember amperage draw in excess of 10A will damage DVOM. Use inductive amp probe of DISplus when amperage draw is high. When using DISplus inductive probe, clamp on negative battery cable with arrow pointing away from battery. Switch off all consumers. It is not necessary to disconnect B- from body when using inductive probe
• Connect (-) test lead to negative battery terminal and (+) test lead to a known good ground.
• Ensure all systems are OFF !
• Be sure DVOM is on and set in proper mode.
• Disconnect battery ground lead from body.
• Observe meter reading, wait for vehicle to enter sleep mode.
• Identify faulty circuit by disconnecting fuses, relays, control modules or connectors, observing meter readings.
• Defective circuit is found when current is below maximum closed current for vehicle being tested.
Details here http://www.e38.org/battery.pdf

[B328iC]

After weeks of chasing around the electrical system and finding absolutely nothing. Have my battery checked and guess what. It's bad. I bought a Bosch battery as I thought they were good. Come to find out they don't manufacture their own and only put their label on it. First one failed after 42 months and the replacement only lasted 18. Now switching to a Champion. Let's see how this one goes.

[zellamay]

Just to add to the diagnosis: Mine also seemed like a parasitic drain. Same symptoms as op. I bought a good multi-tester, pulled all fuses/relays, one at a time. Nothing. Finally tested the 24 month old battery: Failed. New battery, problem went away. ... If that ever happens again, I'll test battery first. It's easier.