Question about battery drain

[evilnickwong]

My E30 battery tends to die down if car is not started in 4-5 days.

I used a multimeter to measure DC current i series with the battery, the reading is 65 mA. According to guides online, the normal current drain for a car when it's turned off is 25-50 mA, so this seems to be too high. If I remove fuse #21, the drain drops to 4 mA.

According to manual, fuse #21 powers the interior lights, trunk lights, torch charger, glove box lights, radio, clock and on board computer.
None of my lights stay on when the car is shut off, clock only using about 2mA, on board computer I did not remove, but I assume it should be fine.

That only leaves the radio, mine is a Kenwood unit, does this mean whoever installed the radio did not do it properly, or perhaps it is old and is no longer entering standby mode properly?

[reelizmpro]

Make sure your trunk light is going off by adjusting the latch so that the trunk goes down far enough. Over time, they become loose and may not turn off the trunk light when closed.

[evilnickwong]

Yeap I've verified that the trunk light shuts off when the trunk is closed.

Is 65 mA considered too high for E30s? It's a 1991 318i M40 engine btw. I assume it is too high since I would expect a car battery to hold its charge more than a week even when not in use.

[Van Westervelt]

Easy way to verify if its the deck or not. Pull the deck and remeasure.

[evilnickwong]

Hmm yes I did think of that, however, I don't have the DIN keys/hooks to remove the Kenwood deck. Is there any DIY way I could do it? Otherwise I'll have to make a trip to some audio shop to get it pulled.

[Garageaholic]

No no no my friend. Just carefully pry the deck out with a flathead screwdriver.

[Jean]

Stock deck? Small allen will work to get it out.

[Van Westervelt]

That only leaves the radio, mine is a Kenwood unit, does this mean whoever installed the radio did not do it properly, or perhaps it is old and is no longer entering standby mode properly?

Stock deck? Small allen will work to get it out.

[Simon S]

Man - if you'd post up some pics of what you're working with - it'd make it easier for us to help.

Some decks - I use two sharp pics on release sliders on either side
Factory decks - yes- small allen key
Most - have a 'sleeve' around the deck - which - yeah, get something thin, small, and flat to pry/bend "attachment hooks" away from panel to release deck.

I suppose if you were desperate enough, you could pull the instrument cluster to be able to reach stereo wires "in and from behind"

On a closing note - if the car was garage-parked - one could put a trickle charger on the battery to compensate if needed..

[Simon S]

Out of curiosity - do you have a torch in the torch charger?

[Lof8]

Out of curiosity - do you have a torch in the torch charger?

I've been dealing with a slow battery drain for a long time. I do not have a torch in the charger. Can this contribute somehow?

[b*saint]

I left my torch in the woods last time we went on a BMW sponsored witch hunt.

[evilnickwong]

OK back with updates. I managed to pry the Kenwood deck out just like FrankM E30 said. It was just friction fit into the sleeve. I disconnected it, drain was still at 61mA. I disconnected my ECU, drain still at 59mA.

Then I disconnected my instrument cluster. Lo and behold, it drops to 1mA. So now that I've found the cause, I need to know how to fix it. What could be causing the cluster to pull so much current when the car is off?

I dont see any lights in the cluster turned on and the needles are all definitely limp, so can't think of anything else to check.

[Conster]

My 325iX had the same problem seven years ago; the battery will drain to a point the E30 won't even start. The BMW technicians told me it was an electrical ground causing the battery drain; they fixed the problem but didn't tell me how they did it.

[Lof8]

OK back with updates. I managed to pry the Kenwood deck out just like FrankM E30 said. It was just friction fit into the sleeve. I disconnected it, drain was still at 61mA. I disconnected my ECU, drain still at 59mA.

Then I disconnected my instrument cluster. Lo and behold, it drops to 1mA. So now that I've found the cause, I need to know how to fix it. What could be causing the cluster to pull so much current when the car is off?

I dont see any lights in the cluster turned on and the needles are all definitely limp, so can't think of anything else to check.

Thats definitely interesting. I thought my drain started after I pulled my cluster to hook up the "vehicle speed signal" from the tach to my wiring harness after a 24v swap. I initially thought the drain was due to the vss wire I had hooked up. Every source I checked said that isn't possible as the connection isn't powered at all. Maybe I bumped/changed something in the cluster.