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1983 300D electrical problem

I bought a 1983 300 D about a month and a half ago, and it was running fine for the little I drive around town... until: I used it on a road trip. I had noticed the red battery light on the dash before, but the car ran fine and the battery seemed OK. Then after driving for about

1.5 hours, the blinkers stopped, the headlights stopped, the radio stopped... and when I tried to start the car after turning it off, the battery was dead. I charged the battery, and the car has worked fine for the past week, driving around town with perhaps 6 start-ups. But the battery light is still on, and I worry that the car is just running on the battery, and I may get stranded.

All fuses are intact. The battery is from 2004, fairly new.

When I disconnect the battery while the car is running, all electrical equiptment stops working-- is this normal for this car, or is it a sign of some problem with the alternator?

My mechanic, over the phone, said I need to replace the alternator-- do you think this is necessary? Any tests you'd recommend first?

Thanks, Kate

Reply to
Kate
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Any reliable garage/store/etc. can run a fairly simple test to determine the condition of a battery. A 2004 battery shouldn't fail this quick unless it was a very cheap battery, most are guaranteed for 4 or more years. Generally the alternator can't be checked if the battery is dead, so a BMW tech old me, and I don't think he was selling batteries.

I've seen AutoZone techs offer to check batteries, etc. in their parking lot, NAPA might also. Give either a call and ask. Let your fingers do the walking in the yellow pages to find the closest. ;-)

And good luck, don't become a damsel in distress!

Reply to
Don.

The red light isn't the battery lamp, but the alternator lamp. It burns when the alternator doesn't generate enough current to charge the battery. The 300D motor doesn't need electricity do run, only to start. And you need electricity for lights, A/C, windshield wipers and so on. You can start your engine a couple of times on a good battery, but when it is not recharged by the alternator, it will go dead.

Don't disconnect the battery when the motor is running, it can damage the alternator and other electrical equipment.

Your mechanic is probably right: your alternator needs to be replaced or repaired.

Reply to
Govert Schipperheijn

I agree. This is almost undoubtly the altenator. You can charge the battery enough to make sure your car will start. Then connect a volt/ohm meter to ground and the positive battery terminal with the engine running at roughly twice idle speed. You should see between 13.5 and 14.2 volts. If not your altenator is not working. Simply replace it and you should be in fine shape. Let us know how you made out.

Reply to
Ernie Sparks

Kate

Sounds as if your alternator is due for inspection. But before you go replacing it, you should check that all your cable connections are sound. The alternator warning light flickers occasionally in my 1985

300TD but I can usually stop it doing this by giving the cables a firm push and wiggle at the alternator housing. Side of the highway stuff, but it works.

Don't know whether these MB alternators use bushes to collect the current from the armature, but if they do, perhaps yours are just worn out. Replacing them will be considerably cheaper than replacing the whole alternator.

Good luck

Euan

Christchurch, NZ

Reply to
Euan

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