possible battery drain

[Tristan36]

Hi everyone quick question I think I may be getting a drain on my battery its pulling 50 milliamps so i was wondering what everyone else see's on there e34s? i read that up to 50 milliamps is acceptable on most cars.

[shogun]

that is fine for Closed Current Draw Test

Maximum closed current by vehicle
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.

use this link for more details http://www.e38.org/battery.pdf

[moroza]

Note that an open door will cause a small current draw. If you're getting 50mA with a door open (or within ~30 seconds of it closing), your electrics are healthy.

[fo3]

Hi everyone quick question I think I may be getting a drain on my battery its pulling 50 milliamps so i was wondering what everyone else see's on there e34s? i read that up to 50 milliamps is acceptable on most cars.

Haha, mines 0.17A and kills batteries unless I put it on a charger every 2 weeks.
It has aftermarket car alarm (only keep for remote locking), aftermarket stereo with amp and sub, and a hardwired 5v USB point that's always on for a dashcam.

E: just got bored so I went out and fixed it. Fuses 22,24 (trailer, headlight washer, wiper pressure system) and 26 (cig lighter) were the problem. None of these things work on my car so I just pulled the fuses and battery drain is now down to 37mA.

[The Chauffeur]

Just an FYI if you do have a drain:

When I got my car, it was sold to me as "with an electrical problem", turned out to be, the CCM was draining the battery. I got a used one off ebay and the problem stopped. A year later (2017), the "new" CCM started draining the battery, too; I got another used one, and it hasn't had a problem since (so I assume CCMs tend to do that??? )

[fo3]

I haven't had that problem with a CCM, but check you have the right type of relays in the right spots. I think I just traced my problem to a relay fitted where it shouldn't be. I haven't driven my car for 2 days and there was a warm to the touch relay in the aux fan relay box. I figure that shouldn't be there for a base 525 - only the two aux fan relays should be there. That 3rd spot is for optional headlight washers and if a relay is there it shouldn't have been warm to the touch so I just removed that as well as leaving the fuse for it out.

I went through the relays in the main box last year and replaced all the wrong ones, like fitting the 5-6pin yellow one that should have been in the blower spot but a regular 4 pin orange one was there, the different pinned mustard colour one that should be in the 'unloader' (or something like that name, which involves LKM and CCM) but different relay was there.
No idea what changing these to the correct type did - everything seemed to be working fine before with the wrong relays regardless - but these special relays have diodes, resistors and extra pins sometimes that could affect parasitic drains I guess.

[moroza]

One more datapoint: I had a climate control module that always kept the interior temp sensor fan running. The solution was to rewire the module so that two always-hot wires came from a hitherto unused fuse (F47?) that was ignition-only. Solved the problem and put an end to random stepper motors humming after shutdown too.

0.17A = 170mA. 24hr/day * 7day/week * 2 weeks * 0.17A = 57.12Ah, which will drain a brand new non-deep-cycle ~90Ah battery (about the capacity of ours) to the point of being unable to start the car.

My '81 Yota draws 2mA, and I think most of that is the mud all over the engine bay. My '73 Ford, after I basically fabricated a new wiring harness for it, draws 0.000A (measured), or 0.000025A (calculated using ~500kohm measured resistance with everything off except the voltmeter).