Weak battery headzup! [SMG stuck in gear due to battery drain] - The Unofficial BMW M5 Messageboard (m5board.com)

Mr. Vroom · 11th May 2007, 17:54

My battery died last nite, but before the car completely shut down, the beast did some very wierd and dangerous stuff.

After starting the engine, the red cog light came on and advised moderation..... I moderately placed her in reverse and eased back out of my parking spot. I then placed it in first, but the car remained stuck in reverse gear. With the dash light indicating first gear I gave it some gas and the car went backwards. I nearly hit another parked car!! After that I shut down the car, waited a few minutes and tried starting it, but it died completely.

This morning roadside assistance came by to give me a boost and perfom a battery diagnosis... The battery drain test indicated "suspect", meaning the car draws too much power when it is turned off.

I recall another thread with a member reporting the same problem with being stuck in reverse. BMW needs to get on top of this, some one could get hurt....

unfoundhorsepower · 11th May 2007, 18:15

Many ,many things could have lead to your problem, just a run down battery could do it !!! Get it checked out.....not by the guy who is towing it !!! a DEALER...If your car sets more than 4 days I would put a trickle charger on it. The M5 does have a heafty draw to it, and has a heafty battery in it....but, don't forget, when the battery is low, you will get crazy sh-t happening to the car and crazy red cogs happening !

Mercedes has TWO batterys in some of their models, JUST to handle the computors., maybe BMW needs it too !

Mr. Vroom · 11th May 2007, 20:14

Thanks, the car is going in on Tues and a trickle charger is a good idea too....low voltage is definitely the weak link in modern cars.... Any one remember Audis problem with spontaneous acceleration??? BMW has significant liability issue here.....

Wayward · 11th May 2007, 22:58

As to trickle chargers and by way of recommendation, I've gone through several over the years and though I like the Ctek models, I recently picked up a Husky charger from the Home Depot and can highly recommend it. Around $60, and it also provides alternator and digital voltage checking as well as a 60 amp engine start boost feature.

boarder1995 · 11th May 2007, 23:02

I've had good success on my ski boat with an Interstate battery charger. Typical auto on/off with some sort of pulse algorithm (I think this one has it). Anyway, it's compact and would likely fit in with the battery, then just run a cord out of an easy access location.

Clyde · 12th May 2007, 00:46

BMW sells a trickle charger as an accessory. It is BMW labeled version of the Battery Tender. I have used the Battery Tender on many different cars, it is an excellent product.

T Bone · 12th May 2007, 02:34

Hey look at what this joker wrote about trickle charging.....

http://www.m5board.com/vbulletin/sho...11&postcount=4

Looks like it need to be right on the battery.

Wayward · 12th May 2007, 04:30

Quote:

Originally Posted by T Bone

Hey look at what this joker wrote about trickle charging.....

http://www.m5board.com/vbulletin/sho...11&postcount=4

Looks like it need to be right on the battery.

Yep, that's what I (<-- subtle link) said -- and kudos on the research T-Bone

!

In the case of our cars, it illustrates the problem with cigarette lighter adapter based chargers -- pretty useless unfortunately (unless one's livin' in gator -- make that gator clip -- parts of the country -- ok, that was bad, sorry).

And of course, you just knew I had to post a few photos...