Battery Problems with a Tested "OK" Battery and Alternator

[DNBtexas]

I have a 3.0 liter 2005 X5 that I got in 2007. 11 months ago, my car died a couple of times in a month, and I had the battery replaced and all was well. In the past two months though, I have had by car not start pretty consistently, and many times turn the engine over but you can tell it’s struggling.

Since I still had a warranty on the battery installation, I took it back to the dealership and they tested the battery and alternator and did a few of the major draw tests (but did not do a comprehensive draw test) and everything checked out as OK. Their explanation is that since I only drive around 10 miles a day during the work week, that the car isn’t being charged back enough after I drive it each time.

The dealer fully charged my battery 3 weeks ago after the tests, and it worked fine, until I left for Thanksgiving for 4 days and came back - it was dead as a doornail. I left the car idling to charge it back up for almost an hour (I just ordered a trickle charger yesterday) and it started once, but then this morning it was dead again.

The only things I leave plugged into my car are a tiny Bluetooth charger (plugged into a cigarette lighter USB adapter in the back of the console) which I always unplug if I know I won’t use my car for 24 hours or more, and I also have a cell phone charger hardwired (below and left of the steering column via an inline cigarette charger socket with the charger plugged into it). A bizarre thing I noticed is that if I turn the ignition and remove the key and I have my cell phone plugged into the hardwired charger, all of the lights stay on etc., but right when I unplug the phone from the charger the cabin and dash lights turn off.

I wanted to see if anyone else has had a similar problem in general or could explain the end of the above paragraph to me, or had any suggestion on what to do short of a full draw test on the car (which is very labor intensive and therefore expensive). Much appreciated!

[SlickGT1]

I had this problem on my old car. Drove it way too little, and it would kill the battery all the time. Trickle charger is the way to go for us bud.

As far as the lights staying on, can't comment on who, what, or how wired up all that. That's something you need to whip out the volt meter and start testing.

[recklessspyder]

You could have parasitic draw from somewhere. Do you have a bluetooth module? Read up on FSR (final stage resistor as well). My bluetooth (TCU) created a parasitic drain. Either unplugging it or pulling the fuse worked for me

[DNBtexas]

An update:

I took the car into the shop that hardwired my cell phone charger and they said that the socket they installed was not drawing any power after the car is turned off. They did, however put a voltameter between the batter terminals while the engine was running and it came out at 13.3v - he said that it should be at 14.6v. Any ideas here?

Also, I was a little mistaken about the cell phone sequence of things in case anyone has any idea what this is about. I leave the cellphone in the dock which is hardwired, turn off the car, the cabin lights come on and the dash lights go off, but the steering wheel stays down until i pull the phone off of the dock (same as unplugging it essentially), then it goes up. I dont understand how the thing would not be drawing power, yet still be able to affect power to the steering column.

Help appreciated. Thanks.

[DNBtexas]

Also, no OEM bluetooth module, just one that i have plugged into a cigarette socket.

[chasz17]

I'd have the charging circuit checked again. Every BMW I've ever owned has had a voltage at the battery terminals at idle between 14.4 and 14.6 VDc.

Also, can you disconnect all the aftermarket items for a couple of weeks to try to isolate this?

[DNBtexas]

That's a good idea on disconnecting. I have disconnected the bluetooth for several weeks, but not the phone charger. It would be a good "control" for sure.

My question is that if at idle the car is at 13.3v, then this is probably an alternator issue, right?

[Quickid]

Originally Posted by DNBtexas

My question is that if at idle the car is at 13.3v, then this is probably an alternator issue, right?

Alternator might be the likely issue but 2 years ago, my E46's battery exhibited the same symptoms and it turns out one of the cells is dead so it's not getting fully charged.

[chasz17]

Again, I'd suggest a professional diagnosis as to why you're at 13.3VDc and not nominally at 14.5VDc. There is an issue somewhere. It could be something like Quickid stated...