535 is eating batteries

[bugger me its bust]

Any help with this gratefully accepted, my 1989 E 34 535 i has taken to discharging the battery overnight, draining it to zero volts, the battery is a new Yuassa correct heavy duty one, every now and then it does this, I have but an ammeter inline and monitored it for several hours and never seen more than 1 amp drain at any time. I have tried removing the wires from the alternator and still it will drain the battery overnight, no fuses are blowing, nothing appears to be running. Any ideas ?

[shogun]

this might help
http://www.bimmernut.com/forum/5-ser...omponents.html

[whiskychaser]

IIRC Bentleys says around 0.1A is normal and above 0.5A needs investigating. FWIW, I get 0. I'd hook up the meter in line on amps range then pull fuses to see when it stops ditching power. In my experience, radios are good at draining batteries even if they are switched off but dont let that distract you

[bugger me its bust]

Thanks for the info and help with this, as I said before after things have settled down the draw of power is below 1 amp, and all seems fine but once in a while the battery becomes fully discharged overnight, given the size and capacity of the battery it must be one hell of a load to drain it down in a short time, its making the running costs in batteries expensive, I have already had one changed under warranty its unlikely this one will be given the same benefit, if it continues without getting resolved I can see myself having to scrap her, thanks again.

[shogun]

way too much, mode 30-50 mA is alright.

Typical suspects are heater valves and IHKA.
Heater valves: I assume you have the IHKA AC system with the control panel like this
http://bmwe32.masscom.net/johan/ihka...emp_sensor.jpg
before you stop the engine, switch the driver side temperature control to maximum heat, over a small resistance. This is the emergency heating, that overrides also the passenger side setting and the heater valves are fully open = without power. Or disconnect the plug from the heater valve, same effect.
If that helps, you found the problem, heater valves are always on, even when engine is off.

Next is the IHKA control modul, that has in total 4 plugs, 2 on the right side, 2 on driver side. You can unplug for example 2 on one side for one night and test, next night, the other 2.
Pinout of the IHKA control module
http://bmwe32.masscom.net/johan/ihka/control_unit_1.jpg
http://bmwe32.masscom.net/johan/ihka/control_unit_2.jpg
white connector X610 'A'
1-4 stepper motor fond area
5 heater sword
6 aux fan
7 rear window heater relais
8 climate control relais
10 NC
11 NC
12+F20 (30)
13+F20 (30)
14 - 17 stepper motors for air distribution (recirculation)
18 light switch LED
19 light switch LED
20 TXD
21 water valve left side
22 aux water pump relais K8
23 water valve right side
24 front window heating relais K8
25+F20 (30)
26+F20 (30)

Blue connector X613 "C"

Pins are in such way
13 up to 1
26 to 14

1= ground
2=ground
3= NC
4=temp feeler driver side
5= potentiometer blower motor
6= temp feeler in engine room
7=outer temo feeler
8= potentiometer temperatur driver side
9=NC
10+,11+, for stepper motors
12+F21 (15)
13+ F21 (15)
14= ground
15=ground
16= potentiometer+ feeler ground
17= potentiometer flappers
18 temp feeler left
19 starter (50)
20=potentiometer+feed
21 temp feeler inside
22 temp feeler reight side
23+ for stepper motors
24+for stepper motors
25+26 = F21 (15)
26+ F21 (15)


green X611 „B“
1 to pin 14,15,16
2,3,4,5 mixing flap motor left
6,7,8,9 fresh air stepper motor outside
10 NC
11 NC
12 NC
13 NC
14, 15,16 with pin 1 legroom stepper motor left
17, 18, 19, 20 defrost flap stepper motor
21, 22, 23 fresh air stepper motor left
25 NC
26 NC

yellow connector 614 „D“

1,2,3,4 legroom stepper motor right
5 MPX button
6 MPX button left
7 MPX defrost
8 MPX button right
9 speed signal
10 RDX
11 button rear window defogger/defroster
12 MPX button recirculation
13 MPX button aircon
14, 15, 16, 17 fresh air stepper motor right
18, 19, 20, 21 mixing flap stepper motor right
22 NC
23 NC
24 NC
25 NC
26 NC

The connectors are:
13 12 11 10 9 8 7 6 5 4 3 2 1
26 25 24 23 22 21 20 19 18 17 16 15 14

See the connectors, they are marked with small numbers outside

The the heater sword, if your car has it

the SWORD has a 5 pin connector

Pin 1 connector for the potentiometer for speed regulation at the control panel.

Pin 2 power supply

Pin 3: the relay get's contact when the blower fan potentiometer is adjusted, 12 volts come on.

Pin 4 is ground

Pin 5 the cable/wire from the blower fan.

Remove the plastic covers from the sword and connect it again to the control panel.
Use a multimeter to test it.
When you turn the thumbwheel at the potentiometer, the voltage at pin 1 changes from 1.1 - 4.25 volts. As the transistor, which amplifies the potentiometer, only has a voltage (input) of 5 volts, that should be the full power of adjustment.

In case the blower fan only starts at let's say 3.5 volts then the pre-amplifier IC (I think it is IC LM 139) is defective. There are 2 pre-amps installed. Cost around 2 $ if you do it yourselves.



BMW E34 Website

[Tiger]

If you have any aftermarket stuff... disconnect them to see if that lowers the draw. Sounds like you only got an analog multimeter... go get a digital one.

[whiskychaser]

Just re-read the original post and something is wrong here. So some thoughts:
A discharged battery should still show about 11.9V and not zero. If it is indeed zero, it will not come back from the dead
Is the electrolyte cloudy? Have you checked the SG reading in each pot?
It occurs to me that if you have, say, a 65 aH battery, then even if you do have a one amp discharge, it should obviously take 65 hours to discharge and not do so overnight.
Have you checked the voltage across the battery with nothing on, then with the engine running, then with the engine running, headlights, fan, hrw on etc?

[bugger me its bust]

Thanks for this info,I am going to be having a closer look at things as soon as my schedule allows, thanks again. I should also say I dont have an AC or the fancy auto facility for climate control just the regular heating controls.

[bugger me its bust]

The battery shows zero when discharged, as I said earlier it drains down to zero overnight and I mean ZERO, no volts, zilch, bugger all. When this happened before I checked the charge rate with everything running and it was charging ok, I then ran a digital ammeter in series to monitor discharge with everything switched off,once the car had gone through its regular shut down procedures the discharge was well bellow an amp more like milliamps for several hours, I duly put it all back to normal and found the next morning the battery had drained down to zero volts this was the final straw for the battery and was indeed dead, it was replaced with a new high spec heavy duty battery and all seemed fine for a few months until it started doing the same the other day.

[Tiger]

There is a possibility that your starter is at fault... random or constant... I had a starter that turns over my engine... seeemingly normal speed... engine starts no problem but my battery continue to die prematurely... won't last 2 years... until my starter died... I put in a newer used one... and the engine spins twice the speed with old battery.

Check the cranking voltage... meanign measuring the lowest battery voltage while cranking/starting engine. If it hits below 10V... you either got a bad battery or a bad starter.

Make sure you do this test with a fully charged battery. My theory is that the amperage draw during starting is too high that kills the battery.