hey everyone. long time
i have a crazy charging issue with my e60. Sometimes it doesnt charge at all and sometimes the battery drains overnight. But not all the time. I had the battery tested recently and its something like over 85% good. The battery is 14 months old.
Yesterday i had to jump start the car.
Fist i disconnected the IBS because it was draining some 6-7Amps. Started the car with IBS disconnected and when i removed the jumpstart cables the engine went off in like a minute. The car wasnt charging at all. Voltage was 11.4 or something.
I switched the donor car to an older one and managed to start the car again, this time with the IBS reconnected. This time the alternator was charging with 80-90Amps at first and later with about 50-60Amps. Measured with a clamp-meter. Voltage was 14.1-14.3.
Left the battery yesterday at 12.8V after car going to sleep. This morning it was 12.3V. Started the car but it wouldnt charge. Voltage was jumping around from 11.8 to 13.0 or something and charging current was alternately 0 or about 40Amps.
I read a lot lately on the subject but i dont know what's the cause here.
Should the car charge with the IBS disconnected?
What can cause the output voltage of the alternator to go from 11.7V (or whatever the battery output is) to 14.7 like 10 times in 20 seconds?
Can you give me some hints please?

 

You can see here the behaviour that only happens some of the times. The rpm needle moves up and down as the alternator is working or not. Is this normal?

 

In my case
I replaced the voltage regulator.

 

In my case it was the alternator itself that needed to be replaced. A new alternator or remanufactured one will come with a new voltage regulator. Depending on the age of your current alternator, may be time to replace.

 

Very similar to my case also. Replaced alternator at 290 000 kms. The alternator had a lot off oil on it due to timing chain cover gasket leaks.

 

Started the car this evening and the alternator is charging. 14.2V. Current was 50 Amps with battery having 12.6V before starting the car.
Locked the car and after 5 minutes the current drawn from the battery was 100-150 miliAmps. I'll check a few more times before going to bed. I believe i have both a charging issue and a parasite current draw. Both acting randomly. So if i get some current draws i'll check the voltage drop on the trunk fuses.
The alternator is the original one. I'll try to take it in service this week. I'll probably put on a new voltage regulator just in case.

 

It seems to me a regulator issue only

 

The battery was completely drained on Sunday. I'll keep monitoring until i replace the regulator. I measured the voltage and amps drawn last night and this morning.
5 minutes after locking the car the amps draw was very close to zero. 1 hour, 3 hours and 9 hours after locking the car the amps draw was 0.150-0.250.
Voltage was 12.85 after locking the car and 12.82 this morning (some 9 hours later). So no loss overnight but i'll keep monitoring it for a couple more days.

 

Ok. So after 4 days of measurements, the battery lost about 0.1V every day and the current drawn was between 0.1-0.25 Amps, tested 3-4 times everyday.
I'm waiting for a free day to take off the alternator and take it to a shop that is specialized in testing and reparing alternators.
Having the battery completely drained on Saturday also caused the car to show a key error message. After charging the battery, the remote on the key would not work anymore. Tried last night the initialisation process but i couldnt get the remote to work. I left the key in ignition position 1 overnight trying to recharge it. I also hooked a battery charger under the hood. This morning, some 10 hours later, i found the battery completely drained, showing only 5 volts. The charger was supplying some 4Amps and it turned off when the battery dropped bellow 10V. Also i found the wipers blades up on the windshield at some angle. Can i do something about the keys?

 

Do you have oil leaks or had oil leaks? I had an oil leak on oil housing gaskets all that oil accumulated in the alternator and burned the coil lines had it rebuild and working like a champ.