more battery problems here!

[hedpe]

Hey all, this is kind of weird, never had it happen to me before. I was driving (89 300SEL) and it seemed like my battery died. I was driving down the road, first my front speakers went out, then my back, then no sound, then i checked my windows, they went up ever so slowly, my SRS light and my ABS lights came on, and no power would work, but i managed to drive it home. I turned it off and tried to turn it back on, it wouldn't. I let it sit for 20 minutes, and tried again and it started. I let the car run for a half an hour to juice the battery back up, i locked the doors with another key and left it sit there. I went back to the car after a half an hour, unlocked the doors, when i unlocked the doors the engine stopped again. Now it won't start at all. Do i need a new battery? Help!

[Mike Richards]

You may have a faulty voltage regulator. Often times the presence of the ABS/SRS lights is an indication of this.

Wen you first turn the key in the ign. switch to the 1st position, you should see most all of the idiot ights illuminate. If you only see the ABS/SRS, you could be looking at bad brushes that are in the voltage regulator.

[JDUB]

You may be able to fix it by replacing the brush holder assembly in the alternator. Yours may be different but on mine you can remove two screws and replace the old. Buy your parts here at Fastlane.

[hedpe]

Hey guys, to make sure it wasn't the battery, i got a new battery. I was driving in to school this morning and plop, everything went down again, so it can't be th e battery. Anyone know the part #? Is this a mercedes specific part? Or could i get it at a pep boys/auto store? Because I need the car ASAP Let me know, thanks!

[hedpe]

Oh yeah, and only the SRS and ABS lights come on, so i think it's what we're talking about. Is there anyway i can open it up and look to see if it is broken?

Like JDUB said - before changing alternator try regulator- if it is a Bosch - on the back of the alternator is a black disk about 1 1/4" round with a flange and two 1/4" bolt head screws holding it in. Take out the two screws and tilt the assembly towards the center of the alternator to remove it. If the brushes are very short - definately the problem. On new unit they are about 3/4" long. Changing this regulator assembly is the cheapest and easiest thing to try first. Remember to disconnect the battery before removing the regulator.

[Mike Richards]

See this thread for how-to instructions:

91 300SE electrical problems?

[hedpe]

Couple more things, is the alternator (Stock I suppose) in an 89 300SEL big enough to carry the voltage (or whatever else kind of power) to power a laptop. Because i hook my laptop up to the car and it sucks up power. Is it only going to kill it again? Or should it be alright after i fix the brushes?

Also, is the car ok (if it starts) to drive about 15 miles home? Am i going to damage anything by driving it? Let me know, thanks! And i'll check out the instructions.

Where can i get the replacement brushes and everything for the regulator?

If your alternator is putting out as it should and your battery is good - your laptop should work fine with engine running. Driving 15 miles with no alternator output???? Scary with battery not at full charge. Make sure your battery has a full charge before starting this trip and turn off heater fan, radio, rear window defogger and all lights so you have minimal drain on battery and you should make it OK.

[hedpe]

Okay i'm going to try and make it home, so all i need to do is replace the brushes correct?

Yes - first step. If voltage on battery with car running after installing brushes is 13.2 volts or higher - you have it made. Check the voltage after you change the brushes and let us know

[hedpe]

Hey, this may sound stupid to you guys, but i've never had to work with an alternator or regulator before. Where are they, and how do i get to them =P

[hedpe]

Hey, i found the regulator and took it off, the one brush is very black and warn out it looks like, so i'm guessing this would be it. How do i replace it and where can i get the part? Does a normal store sell it? Get bosch?

[JDUB]

Hedpe, I now think you realize how easy a fix this can be. If you need the part quick get it at a foriegn (german) auto parts store or at a Mercedes dealer. They usually will have this in stock. Let us know how it turns out. If one of the brushes is black it is definately "smoked". Good Luck my friend.

[JDUB]

By the way you can get one at Fastlane here for about $15 German no name brand. (i bought one) or a Bosch for about $45. You be the judge. I have a spare car if mine goes down.
If the cheapo reg don't work you may have a problem in the alternator.