85 240 DL Battery going dead

Hi there,

Recent rebuild on this car, 300000kms. Auto
Trannie, B230F motor. Sedan. 3 spd trannie.

The battery goes dead after about 10 hours of not running. Put my
multimeter on it, when running
the voltage is 14 volts, which rules out the
alternator. When not running, I can observe the
voltage dropping from 12.75 to about 12.30 or so.

Amperage drawn when the car is not running is
0.8 to 0.87 Amps, which shouldn't be enough to drain the battery in 10
hours.

The battery is brand new, and I realize it could
be a dud. However, are there any other things
I should be checking?

Thanks
t

 

0.8 Amps is a lot of amps. I'd expect something less than 0.05 amp.

Try pulling the fuses until you find the culprit. In my '89 240 it was one
of the door-is-open switches.

 

I concur with Robert L. It looks to me you have what is known as
parasitic battery drain. Something is staying on after the ignition is
off and the car locked up for the night.

I've often seen this happen and many times it was the glove box light
staying on as the switch was bad.

As Rob suggested, start pulling fuses one at a time for ten hours
until you find the culprit.

Good Luck,

Doc

 

After taking all of your advice, we found nuthin!

BUT, there is this blade fuse in line with a wire
coming directly off of the positive terminal of
the battery. Apparently, it feeds the fuel pump
relay? Its a 30 Amp fuse.

Anyways, when I pulled that fuse, the draw on the
battery went from 0.87amps to 0.01amps. I'm
thinking my problem is there.

Any ideas on how to fix this? Once the power goes
to the relay, where does it go from there?

t

 

It could be a rotting insulation in the wiring harness in the engine bay. I
had the same problem and I knew that the harness was rotting but didn't
replace it in time. One fine Sunday morning the car caught fire just sitting
there stone cold. Do check.



Regards,

Boris Mohar

Got Knock? - see:
Viatrack Printed Circuit Designs (among other things) http://www.viatrack.ca

 

I just happen to have a wire diagram book for '87 handy. That fuse only
feeds the fuel pump relay. With the key off, check for power at the
following: The red-yellow wire at the injectors and the orange wire on
pin 5 at the air mass meter. If either have power then the fuel pump
relay is stuck in the on position and you need a new one.

Also, assuming the battery is fully charged, then this draw shouldn't
kill it in 10 hours. However, car batteries aren't designed for this
kind of discharge/recharge and can be quickly damaged when subjected to
it.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

 

Thanks Mike! That is great info!

Part of todays exercise included charging the
battery and bringing it in to get it load tested. The alternator has been
ruled out already
(14 - 14.4 volts when the engine is running)

So hopefully we can rule out the battery, but I
also want to deal with this parasitic draw. Until it
is figured out, I will just pull that 30Amp
fuse overnight, so that it can't kill the
battery.

Thanks, and any other tips would be greatly
appreciated!

Terry