2003 M3 flat battery problem

[Andy's ntl news account]

I have a 2003 M3 and in the last 12 months I have done about 7,000 miles. In
the same period I have had to call out the BMW emergency recovery service to
start my car on 8 occasions.

If I leave the vehicle standing for more that 4 days the battery is flat. My
dealer has checked it over twice and says there is nothing wrong with the
electrical system (they also replaced the battery).

The latest advice from BMW is that because my car is low mileage the battery
is never being completely recharged.

I had a 330i before I got the M3 and I did a similar annual mileage, but
never got these problems.

Anyone else have this experience, or is it just my car ?

Thanks, Andy

[Jim Levie]

On Fri, 17 Sep 2004 21:15:34 +0000, Andy's ntl news account wrote:

> I have a 2003 M3 and in the last 12 months I have done about 7,000 miles.
> In the same period I have had to call out the BMW emergency recovery
> service to start my car on 8 occasions.
>
> If I leave the vehicle standing for more that 4 days the battery is flat.
> My dealer has checked it over twice and says there is nothing wrong with
> the electrical system (they also replaced the battery).
>
> The latest advice from BMW is that because my car is low mileage the
> battery is never being completely recharged.
>
When the car is driven how long is the average run? Cranking pulls a good
bit of stored charge out of the battery and it takes a will to put it back.

If, when run, the engine is on for 20-30 minutes the battery should come
back up to a full charge. Assuming that's the case I see two
possibilities. One would be that the alternator isn't charging at full
rate. Another would be that there's an excessive drain when the car is
off. Both of these can be pretty easily diagnosed with an ammeter.

--
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[Dave Plowman (News)]

In article >,
Jim Levie > wrote:
> >> .005 amps is 5 milliamps, not 50.
> >
> > Just checking to see if anyone's awake. ;-)

> Yeah... Like anyone is going to believe that... :-)

Bugger. Found out again. Anyway, 50 mA(ish) is the correct figure.

--
*In some places, C:\ is the root of all directories *

Dave Plowman London SW
To e-mail, change noise into sound.

[Fred W.]

"tech27" > wrote in message
erio.net...
> I had a similar problem with my 97 540. Turns out the bulb under the
> automatic shift display was remaining on all the time. I couldn't tell
> because I always left the car before the dimming was done.
> Doesn't sound like it should be a problem, but it the cause was that it
was
> grounding out, this might have been drawing more power. Battery only died
> after 2-3 days of not being driven.
> I didn't believe that this could have caused the problem, but since it was
> fixed the battery has been fine.
>
> Go figure.

OK:

Even a tiny 1.5 watt bulb (like those used for illumination of the indash
odometer LCD) would draw 125ma of current at 12volts. The bulb under the
gearshift indicator is probably a 3 watter so double that current drain. In
either case, a flat battery would be the results of leaving it on for
several days.

-Fred W

[tech27]

"Fred W." <Fred.Wills@'remove this to reply to' myrealbox.com> wrote in
message ...
>
> "tech27" > wrote in message
> erio.net...
> > I had a similar problem with my 97 540. Turns out the bulb under the
> > automatic shift display was remaining on all the time. I couldn't tell
> > because I always left the car before the dimming was done.
> > Doesn't sound like it should be a problem, but it the cause was that it
> was
> > grounding out, this might have been drawing more power. Battery only
died
> > after 2-3 days of not being driven.
> > I didn't believe that this could have caused the problem, but since it
was
> > fixed the battery has been fine.
> >
> > Go figure.
>
> OK:
>
> Even a tiny 1.5 watt bulb (like those used for illumination of the indash
> odometer LCD) would draw 125ma of current at 12volts. The bulb under the
> gearshift indicator is probably a 3 watter so double that current drain.
In
> either case, a flat battery would be the results of leaving it on for
> several days.
>
> -Fred W

Yeah, makes sense. However, I remember a garage that had a 12 volt radio
hooked up to a battery that was removed from some car, and that radio ran
all day for years on the one battery.

[Somebody]

"tech27" > wrote in message
. verio.net...
>
> "Fred W." <Fred.Wills@'remove this to reply to' myrealbox.com> wrote in
> message ...
> >
> > "tech27" > wrote in message
> > erio.net...
> > > I had a similar problem with my 97 540. Turns out the bulb under the
> > > automatic shift display was remaining on all the time. I couldn't tell
> > > because I always left the car before the dimming was done.
> > > Doesn't sound like it should be a problem, but it the cause was that
it
> > was
> > > grounding out, this might have been drawing more power. Battery only
> died
> > > after 2-3 days of not being driven.
> > > I didn't believe that this could have caused the problem, but since it
> was
> > > fixed the battery has been fine.
> > >
> > > Go figure.
> >
> > OK:
> >
> > Even a tiny 1.5 watt bulb (like those used for illumination of the
indash
> > odometer LCD) would draw 125ma of current at 12volts. The bulb under
the
> > gearshift indicator is probably a 3 watter so double that current drain.
> In
> > either case, a flat battery would be the results of leaving it on for
> > several days.
> >
> > -Fred W
>
> Yeah, makes sense. However, I remember a garage that had a 12 volt radio
> hooked up to a battery that was removed from some car, and that radio ran
> all day for years on the one battery.

The car itself also has a load however, while off, for the various computers
and such. Newer cars are worse than older ones for this.

Personally I always wondered why they don't put two batteries in a car --
one for incidentals and one for starting. That way you can always get the
car going again no matter what happens to the other battery -- which can
then be recharged as you drive. Or, if your driving pattern is insufficient
to keep it charged, it can warn you early enough to do something about it,
without causing you to get stranded. There are a bunch of potential
benefits you could imagine from having two batteries in an intelligent
setup. Yes it's more weight, but they can be located in an advantageous
spot in terms of weight distribution (trunk for example) and won't make a
world of difference on a 4500 pound car anyway. But it would be a truly
useful feature that could be advertised to good effect.

-Russ.