M6 Battery problems...again..

[sundstei]

I started having some problems after the winter when the little Beast was standing for a few months in the garage waiting for summer. I bought a trickle charger and put it to full a few times, but was having problems with it sometimes complaining about battery, and "high battery discharge" was coming in the display sometimes.

So I had the battery changed to an aftermarket VARTA SILVER DYNAMIC 110Ah 920A, and had the local workshop reset the charging profile in the M6 after installation. A few months of use, and it was getting some similar low battery messages, and I kept hooking it up to the tickle charger to keep it running.

About 2 months ago I had the "BMW battery cable" fix done at my BMW workshop. After this it got even worse and the car would several times not even start.

Planning a little trip with the wife into Swiss alps, I decided to make sure and sent the car for full check with BMW. They reported back that the battery was not giving the right "profile" when trying to start, and would need to be changed. They put in an orignal BMW battery, and re-programmed the charging profile.

Car was standing over the night and we started it like nothing this morning. We started driving towards Germany, and after around 400km we stopped at a petrol station and filled the tank. After another 200km we stopped and topped off the fuel before going into Germany. To my horror the car was completely DEAD when starting it up again. Wouldnt even turn on the iDrive screen, and all the lights in the dashboard was flickering a short while.

With the assistance of some nice gentlemen we finally got the car started with jumper cables, and we crossed our fingers hoping it would be done with. Continued into Germany and around 370Km later we stopped at a nice Shell station. Same process again!! And this time the car was even more dead than the previous time. Not even trying a little to charge...

BMW keeps telling me the alternators are fine, and they have no reports of any voltage draining when doing the tests.

I really dont know what to do now.. sitting in little town in Germany called Kulmbach, and searching for BMW dealers instead of enjoying my honeymoon with the wife

Any suggestions are welcomed with open arms!!

[sundstei]

So ... a further bit of experiences..

Day 1

Drove 450km, tanked, wont start, get jump from other car, drove 520km, wont start, get jump from other car, drive 30km to Hotel and leave it in the carpark. Looking around for cars to get a jump from next day.

Day 2

Cold starts in the morning after no charging!! Drive to a BMW center in Munich area and they charge the battery to full. Say they can not find anything else wrong than empty battery. Drive 600km to gassstation for tanking. Car wont start. Getting jump from other car to get back on the road.

So, it does seem like its only discharging the battery when its actually running. The further I drive the more likely it is to discharge. However when the car is turned off, it seems to be holding its charge nicely.

Most of my previous "nightmares" have been: starting the car in the garage nicely, driving 500m to gassstation for tanking up, or to the carwash. As soon as i get in the car afterwards, its screaming that its lost the date. I manage to mostly start the car, but its really on the edge.


As I understand it, the date should disappear only if the battery has been disconnected? All other electronics are working fine when I sit back into the car.

[Clyde]

Originally Posted by sundstei

As I understand it, the date should disappear only if the battery has been disconnected?

When battery voltage gets low, some modules will be powered down to conserve power. The reset date indirectly indicates low battery voltage.

Since the dealer has been unable to solve your problem, you might want to collect some additional data. Use a voltmeter and measure the battery voltage. Verify the voltage is the same at the battery and the jump start points under the hood. Keep a log of the voltage.

The "battery cable fix" increased your problems, so perhaps the recall was not performed correctly. Dealer make mistakes with oil changes, so they can mess up the most trivial task.

[sundstei]

Thanks, Clyde!

Update 3:

This morning I charged the car in the garage until it was completely full. Checked with voltmeter, and it was showing 11.87V. Started and stopped the car 4 times, with no problems at all. Checked the battery and showing 11.7V.

Took it out driving (actually the wife driving...) for 45minutes, and parked it in the garage. Checked the battery, and its showing 8.9V. Tried starting, and it was of course not even attempting.

What on earth can be heavy enough to discharge the battery in just 45 minuttes? And I am imagining also using up all the electricity from the alternator in addition. Everything seems to be working fine in the car while we are driving. Aircondition off, as its a 17 degree day in Warsaw.

[Clyde]

Originally Posted by sundstei

What on earth can be heavy enough to discharge the battery in just 45 minutes? And I am imagining also using up all the electricity from the alternator in addition.

I would guess it is the alternator/voltage regulator.

Another possible cause: The car might be coded for the wrong type of battery. AGM batteries charge at a lower voltage than conventional "wet" batteries.

An M5 owner is having similar problems, still not solved.

[sundstei]

Thanks for the link to the other thread! I have been looking around the forum, but couldnt find anything that was similar to mine.

Last night I left the battery charged in the car over night to see if there was any discharging.

Yesterday at 24:00 :	11,94V
This morning at 09:00 :	11,69V	Same voltage both front and back.
Car running on idle:	10,97V	Message of “High battery discharge” on the display after about 1 minute.
After engine stopped (running for 3 minuttes):	11,53V

[KPG-]

Sorry to hear about your grief.... I just got mine back today and it works just fine so far. After speaking to the tech I will summarize what he said, I dont take it at face value . In the end it was just an altenator issue even though tests showed it to be working fine because the other issue of a shorted out EDC module was "masking" the altenator issue to the diagnostic equipment....take it for what it is worth but my car would be down from a full charge to less <11 volts in 45 min to an hour. Good luck...

[whatheheck]

Battery fully charged should read 12.7 volts.

Your battery voltage is really low, hence the reason for all the electrical faults.

If you are driving your car and the battery continues to discharge, just like Clyde and everyone have already said - most likely your alternator is not charging the battery. My educated guess is its the alternator or battery charging system is going bad, but I would start with the alternator.

Since your battery voltage is also reading low even when supposedly fully charged, then its possible that both your battery and alternator has gone bad.

Keep us posted please.

Dan