Some electrical questions for my E30

[evilnickwong]

My E30 battery tends to die down if car is not started in 4-5 days. Is this normal?I used a multimeter to measure DC current i series with the battery, the reading is 65 miliamps. 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?Next question is that I noticed that some of my fuses don't match the ones in the manual. Some have been replaced with higher amp fuses, and one with a lower one. Are our CKD models here different from the specs in the manual?

 

[jarance]

65mA x 24 hours = 1.56 AH per day. Assuming that your battery is 60 AH, that means that your battery would
be drained completely = 60 AH/1.56 = 38 days i.e. 12 VDC to 0 VDC.
(of course assuming the discharge is linear but it is not)

25 to 50mA (average 30 mA) x 24 hours = 0.72 AH per day. Assuming that your battery is 60 AH, that means that your battery would
be drained completely = 60 AH/0.72 = 72 days i.e. 12 VDC to 0 VDC.
(of course assuming the discharge is linear but it is not). This (72 days) is almost double the number of days.

so check the milliamp when the kenwood HU fuse is disconnect lor.

In reality, the starter will not cranked properly if the battery voltage dropped below 10.5 VDC. or below 85% of the nominal voltage.

 

[evilnickwong]

Hey jarance, thanks for the calculations using battery rating.

I did think of just disconnecting my HU to see if it really is the reason. However, I can't get the HU out to disconnect it since I don't have the proper DIN keys/hooks for it. Have to go to an audio shop for help.

 

[jarance]

Hey jarance, thanks for the calculations using battery rating.

I did think of just disconnecting my HU to see if it really is the reason. However, I can't get the HU out to disconnect it since I don't have the proper DIN keys/hooks for it. Have to go to an audio shop for help.

If I am not mistaken, the radio may have a different fuse beside the common fuse "21" as mention by you.

Which kenwood model? I know that the kenwood can be removed by a flat strip about the size of the backend of a metal spoon
except it is thinner.

I think it involve removing the plastic bezel and slid the metal strip at left and right of the frame if I am not mistaken.

 

[evilnickwong]

It's a KDC-MP4023G. I've removed the faceplate and bezel before, but never had a suitable tool for removal.

 

[jarance]

here is a hint on how to do it.

 

[aidilj]

Had this problem with my E46 after the carputer installation. My problem was the amplifier did not go into standby properly, put a resistor to pull down the stby pin and ok since.

A simple check is to make sure the the ACC line in the car is driven low when the car is turned off, so that accessories are put into stby properly.

 

[evilnickwong]

jarance: I'll try fiddling around with some flat head screwdrivers later.

aidilj: How do you check the ACC line in the car? I would assume it turns off properly, because I have a voltmeter connected to ACC and that turns off properly when the car is shut off.

 

[aidilj]

I would connect voltmeter to ACC wire with all devices connected and make sure the voltage goes to 0V.

 

[evilnickwong]

Yeah it's 0 for sure when key is off.

Anyway, I poked around the car earlier. Turns out the Kenwood HU is only friction fit, so some cajoling with the flat head screwdriver popped it out. I disconnected the HU and measured current again, it was 61mA. A drop of 4mA from earlier. Next thing I tried, disconnected the ECU. A drop of a further 2mA down to 59mA total.

Finally, I disconnected my instrument cluster (removed the blue and white plugs behind the cluster. Lo and behold, the current drain dropped to 1mA.

So the question now is, why is my instrument cluster taking up so much current?!? No lights in the cluster remain on and the dials are all lifeless, so I don't know what is draining the battery.

 

[jarance]

Is there a rechargeable battery in the e30 cluster?

btw, I am shooting in the dark with the above question..

 

[evilnickwong]

Hmm come to think of it, I think from factory, it does have some rechargeable batteries there.
But.. that would mean it's normal for E30s to KO without 4-5 days without starting? Meh. :-/

 

[jumpman]

hm..do u have a voltage stabilizer installed? i have tried not starting mine for 2 weeks and it still cranks up like normal.

 

[evilnickwong]

Nope, I don't have a voltage stabilizer installed. I always felt it was snake oil.

I have a similar thread going on r3v and the suggestion there is that my SI board NiCad batteries in the cluster are going bad and causing the excessive drain. Either need to replace the batteries or replace the SI board with a newer version that uses LiIon batteries instead.
Will have to open it up later to see if its leaking or anything.