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Battery or Alternator?

13K views 67 replies 19 participants last post by  Nordic_Kat 
#1 ·
Yes, I've already done the search, in fact I spent most of Sunday afternoon, while the E93 was stranded in the driveway with a battery charger attached reading two years worth of battery threads; so here goes:

Two or three times in the last 4 weeks the car has choked and sputtered a little while starting, but never has it had significant trouble turning over. I've never had any battery low warnings.

This weekend was car detailing weekend, so there were 4 consecutive starts which amounted to starting the car moving it either out of or into the garage then shutting it off. On the 5th time, when I was finished with my work and was ready to get in the car and run an errand, the car suddenly wouldn't start at all. BTW: I have done this type of pattern of starts and stops before and never had any ill effects.

When we hooked the car to the battery charger on the 6 amp setting the needle immediately pegged at 6 amps and it took about 3.5 hours to get the battery charged enough to start the car up and get it moved back into the garage. We then put the battery charger back on it, on the "trickle" setting and continued to let it charge for another hour until it indicated that it was at capacity. Interestingly, while the car was on the charger in the garage, just doing things like opening the doors, opening the trunk would cause the draw on the battery charger to spike again to 6 amps and then it would gradually return to 2 amps. When charged to capacity, we unplugged everything and let the car sit overnight. This morning, enough charge had dropped that the battery charger was again indicating 3.5-4 amps when attached to the car and plugged in.

At noon we took the car and made a short trip. When SO got back home with it he again checked it with the battery charger and again the charger spiked at 6 amps then slowly came back down to two amps.

THe car DOES NOT have Comfort Access so I wasn't draining the battery with the CA system this weekend. I also do not have i-drive, so no parasitic drain there.

As I am still in warranty, the car is scheduled for a visit to the dealership in the morning, but would appreciate hearing what input knowledgable 'festers might impart.

TIA

-Kat
 
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#61 ·
Kat from what you posted I think there were a few of us that unfortunately felt confident your battery is toast.

Regarding what is better starting the car engine running or letting the battery take the whole load, starting the car and allowing the top to operate is always better because of the huge amp draw the battery receives. The alternator can help catch that draw down up if you let it run a few minutes.

If you can the battery tender is really helpful to prolong life. Mine is approaching 5 years 9 mos and I don't think it would have lasted that long without the tender.

Big question....is the dealer going to cover this or are you?
 
#62 ·
Big question....is the dealer going to cover this or are you?
That's a big question.

Today is 5 weeks exactly from when I first posted about this issue. This morning when I went out to start the car, it sort of started to crank, then it stopped cranking and started clicking and all the dash lights were flashing like strobes, and just as I thought sure it was going to go "all stop" it turned over and started. I drove the 5.5 miles to the dealership and handed over the keys to my SA with a full explanation. As of 3:45 this afternoon, they still could not reproduce the behavior but are keeping the car for further investigation.

While I think it's a red herring, the SA keyed in on my saying that both times this has happened it's been coincident with me washing the car, so they are wanting to check for possible points of water intrusion.

I think it's a weak or faulty cell in the battery, because I've been doing the same type of behavior for 3 years now and it is just suddenly an issue.

I never got a chance to try the good old fashioned "load" test before it choked. I'm getting to the point where every morning when I fire it up, I'm going to have my cell phone capturing a video of the process, so I can catch it the next time it happens and have some solid evidence.
 
#65 ·
Kat,

Hopefully the dealer would have the battery replaced under warranty for you. I just want to add another data point regarding the power draw of the retractable top mechanism. The car and the battery are 6-month-old, so presumably in good condition.

Every time I operate the top 3 or 4 cycles in succession without driving the car, it would show an "Increased battery discharge!" warning on the iDrive screen upon start up with the yellow car-on-a-lift service warning in the instrument cluster. So the top is obviously drawing a lot of power from the battery during operation and the battery doesn't like it at all. The car never failed to start or cranked for a long time, and after driving the car for 15 minutes, the warning message no longer returns when the car is started.

I don't have a good solution, but it seems like this is what it boils down to. The top mechanism draws a lot of power. Someone with a Bentley manual should confirm this, but I suspect the battery capacity for E93s is the same as the other E9x models, and it isn't really big enough for operating the top again and again without the car being driven, especially as the battery ages. A trickle charger hooked up while operating the top while detailing might help, but in final analysis E93 owners would have to accept shorter battery life compared to other E9x.

"Unfavourable driving pattern" is bollocks. If BMW can't make a car that has to be driven more than 5 miles a day to stay charged, perhaps we should all stop buying BMWs altogether. If the service advisor insists this is the cause of battery failure and refuses warranty coverage, I would demand documentation issued by BMW NA or BMW AG specifying minimum driving criteria for battery replacement under warranty. I doubt such a document exists (for it would be absurd), but if it does, it would make a comical read.


Sorus
 
#66 ·
Update: (Subtitle more Horse Puckey)

This morning I got the call that once again the car threw a whole bunch of "Unfavorable Driver Behavior" codes.

The SA point blank asked me if the car doors get opened and closed "a lot" between driving the car. "Well, uh - yes, when I'm giving the car its weekly bath, driver's door gets opened about 5-6 times, passenger door 3-4 times, trunk at least once, then there is the two stage top down to dry and lube the seals, then top up. And yes, sometimes the car gets turned on, pulled into the driveway then turned off. Isn't this normal/usual behavior if you own and maintain a car? Shouldn't a battery be able to deal with this?"

"Well, yes", concedes the SA. "That is why we are going to go ahead and replace the battery in your car and do the paperwork to get BMW to "goodwill" it even though they really don't like to do that when the car throws 'UDB' codes." So, the new battery has been installed but the car is spending another night at the dealership on their monitor to see if it has a phantom voltage sucker.

Now I am in earnest going to finalize a decision about which batttery tender to buy.

It's election night. I think I need post a poll...... :angel:
 
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