Battery appeared dead and alarm going off intermittently

[Savage_M3]

Tonight when I got out from work and approached my car, I heard the alarm sounding intermittently. The doors wouldn't open and I had to use the mechanical key to unlock the car. After that I noticed that none of the interior lights would come on and the car won't start.

Fortunately a coworker was able to give me a jump start and the car started without any problems. I drove home and checked the voltage at the access points in the engine bay and measured about 19-20V while running and 16V when turned off and locked. I used a cheap volt meter, so it might be off by a volt or so.

Any ideas on what might have caused this? The battery is less than a year old. Last winter I would get the "Increased Battery Discharge" warning on cold days and the dealer eventually replaced it for me. I have not see that warning since.

A few additional observations...

- After the jump and driving home the car started up multiple times without any issue.

- It was about 35F outside, so it wasn't too cold.

- Any way to get into the trunk if the battery is dead? You know, in case your jumper cables are back there?

[Savage_M3]

Follow up...

So I found the diagnostic screens on the dash and was able to check the voltage on there.

Before starting up the voltage was 11.9-12.1V

After starting it shot up to 14.8-14.9V at Idle.

[White 13]

Is your normal short trips? That may not allow enough to charge the battery and cause a short life. I have read that many times here.

Can you hook it to a charger overnight? That would be a good place to start trouble shooting. Seems your resting voltage is a little low, should be around 12.3 to 12.6 or so. After sitting overnight you might see even lower voltages tomorrow morning. Running voltage seems a little high but I would have to check what mine does.

Seems these cars have their share of battery and charging problems.

[Savage_M3]

So I started it up this morning and monitored the voltage. No issues starting it up.

It was at 11.5-11.6V before starting the car and then it stepped up to 14.4V. I let the car warm up for 10-15 min and then turned it off.

Do any of you think it warrants a battery test at the dealer? I can try to hook up a trickle charger tonight or tomorrow and see if that helps get the resting voltage back up to the 12's.

[aira]

Take a peek at this thread. I have this same issue as well.

http://www.m3post.com/forums/showthread.php?t=1205470

But basically it's the power cable that attaches to your fuse box. You just gotta give your fuse box a jiggle and it'll work again. If you want to completely fix it, then you'll need to replace your battery cable and connector.

[Savage_M3]

Originally Posted by aira

Take a peek at this thread. I have this same issue as well.

http://www.m3post.com/forums/showthread.php?t=1205470

But basically it's the power cable that attaches to your fuse box. You just gotta give your fuse box a jiggle and it'll work again. If you want to completely fix it, then you'll need to replace your battery cable and connector.

Thanks, I'll check that out tonight. I looked there yesterday and it looked fine, but I didn't try jiggling it at all.

[White 13]

Sound like to do some of the above checks you need to compare the actual battery voltage at the posts with what the car sees. You may need a new voltage meter as yours seemed not up to the job.

This one works for me, $10: http://www.sears.com/craftsman-multi...=DealHeist_New Usually can pick it up in the store and not have to wait for shipping.

Harbor freight also gives one away at times with coupon or cheap otherwise and will work for awhile.

If still having trouble having the battery checked is also a good idea. I think the battery must be charged before testing so it may take a little while. I don't know if the dealer will charge money for that or not. Could be most reliable place to have it done though.

Autozone and Oreilly may also test it for free but you may get what you pay for that way.

Sears also does it but I wouldn't trust them. If it is their battery it is good, some other battery and it is bad; has been my experience.

I take it your driving is enough to keep the battery charged and not short trips or a lot of sitting?

[EnderG60]

I was having intermittent issues with voltage drops, then my battery died.

Turns out water got in my trunk, gave the battery a bath for about a month and corroded the power cable that goes from the batter to the front. Ive heard its common for the taillight to leak into the battery well.

Downside replacing it requires you to basically take apart everything under the car, upside insurance covered the repair.

Hopefully should have it back this week

[vsix]

Originally Posted by EnderG60

I was having intermittent issues with voltage drops, then my battery died.

Turns out water got in my trunk, gave the battery a bath for about a month and corroded the power cable that goes from the batter to the front. Ive heard its common for the taillight to leak into the battery well.

Downside replacing it requires you to basically take apart everything under the car, upside insurance covered the repair.

Hopefully should have it back this week

Telling you what, its one of those rubber gromets from your rear lights that started leaking!

That's where usually water enters your car. Just follow the watermarks on the inner panel and you'll see what I mean.
Just get the rubber gromets properly installed. Best bet would be to use some silicone and apply it around the rubber gromets.

[Savage_M3]

So it happened again today. I went to an appointment this morning and then a half hour later when I stepped outside to go to the car the alarm went off and the car appeared dead again. Coincidentally I monitored my voltages before I started the car and during my drive today and everything seemed fine. 12.3V before starting and about 14.5V while on.

This time a jump didn't even bring any of the interior lights or ignition back. I checked the battery and the connections and they seemed fine. I got a tow the the dealer and they will now look into it.

Interesting thing is that when we got to the dealer, about 30 minutes later, everything seemed fine. Power was back and doors could lock. Makes me think that either there is a loose connection somewhere or that the security system is locking everything out for a period of time. Does the security system perform some type of lockout?

Dealer is swamped, but they hope to get to it tomorrow. I'll post what they find. Thanks for all your feedback!

[Savage_M3]

Originally Posted by White 13

I take it your driving is enough to keep the battery charged and not short trips or a lot of sitting?

I drive it daily. My morning drive to work is only about 10 minutes, but most nights I drive to other places before heading home. Typically 20-30 minutes or more on those drives.

[White 13]

Sounds more and more like the cable that was mentioned above. It would have interesting to get a voltage reading across the battery post just to see.

Kind of a bad feeling when you can't trust that the car will start when you want it to. I am sure the dealer will be able to trouble shoot it. Let us know what it was.

[TTony]

I had the same alarm issue last night. Taking my M3 in for the battery cable recall and that should fix it based on what I've read. The recall is for M3's up to Oct 2011 (my prod date is Aug 2011...).