Battery dead - Not charging ? - PeachParts Mercedes-Benz Forum

ps2cho · #1 01-02-2008, 10:16 PM

Car died today and wouldn't start. Jump started it and it started and ran fine while the battery charger was connected, but as soon as disconnected it, it ran rough and as soon as we puts the lights on, it died.

This is something that started yesterday and the only clue that something was going on, was all the warning lights (ABS, Parking Brake, Low Fuel Lamp (even though I'm full on gas) etc)

Removed OVP, started the car but the warning lights were still on and the tach was reading all over the place.

Checked fuses on OVP, but look fine.
We replaced battery with a fresh one and drove it home.

Alternator bushes were replaced 5000 miles ago. Doesn't look like its charging.

Any ideas?

Thanks,

mpolli · #2 01-03-2008, 01:07 AM

Here is an old thread that might help

More battery/alternator troubles

I will copy the highlights here but you might read the whole thing. Maybe you might find some helpful info.

"The voltage at the battery with the engine running and everything else off and fully charged battery should be 13.0 to 13.8 Volts. Domestic cars will be 14 to 14.8 volts.
With the engine at idle, check for AC voltage. It should be less than 1V. If it is more, than the rectifiers are bad in the alternator. Now back to DC volts at the battery, turn on the lights and the AC fan to high. The voltage will drop but it should stay above 12.5V. Rev the engine to 2000 RPM and the voltage should go back up to 13.0 to 13.8 V. If not, check the alt belt first. It should be tight enought that you can't turn it by hand.(Be careful, it will be hot). If the belt will slip when turning it by hand, it is toooo loose. Tighten it and recheck."

ps2cho · #3 01-03-2008, 01:32 AM

We are getting 12.4v idling and it drops significantly after the lights turn on.

Sounds like my alternators trash huh.

I was just reading through and it says that Amplifiers take a big hit in the amperage. I have a 500w amp installed, so maybe thats taxing the alternator...but then again I think it should still be able to handle it. Maybe it was weak beforehand and this just finished it off after 3 months of the amp.

mbdoc · #4 01-03-2008, 08:00 AM

The "little" alternator on the 1986-89 300E's was not enough power for the car at all.

In 1990 MB went to an 80A version that WILL handle 99% of that cars needs.

ps2cho · #5 01-03-2008, 02:07 PM

Quote:

Originally Posted by M.B.DOC

The "little" alternator on the 1986-89 300E's was not enough power for the car at all.

In 1990 MB went to an 80A version that WILL handle 99% of that cars needs.

Could my installation of my amplifier caused the alternator to die, or do you think it was getting weak beforehand and died due to the extra stress ?

ps2cho · #6 01-07-2008, 10:44 PM

Just thought I'd update for future searches if anybody comes across same problem:

New Bosch Premium 70amp alternator fixed the problem. I am going to buy a capacitor for my amplifier to take the extra load off.

But for the time being I am pretty sure I will be fine. The alternator was still the original one so that combined with the extra load probably caused it to die.