Hi Fellas,

I have been having a weird charging problem with my dad's car see the battery had been acting up and after that the battery now shows over 23 volts!! I think this was after the battery stated to act up and usually after you'd start it would go to around 14 and after sometime it would go to around 12.5 and 11 when the engine is off this is a diesel 90 amp din battery it got ruined sometime ago when the alternator was not functioning properly but the alternator is putting out current now although after the battery had shown such a big voltage now the battery wont hold up the charge well after 2 cranks or one long crank the battery will be dead

Alternator Type:

50AMP
Nine Diode Type With the Transistorized Regulator (not the old type)

PS:It's not a problem with my multimeter

Jeremy Brett

How's the regulator?

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83 SD

84 CD

same with the old and new they dont seem to be faulty
PS:sorry I dont know how 2 thread's came sorry
jeremy brett

The local AutoZoo may be able to help, they'll do a test for free.

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83 SD

84 CD

I'm not in america any suggestions as to why this is happening

I'll take a guess - bad voltage regulator.

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Charles
1983 300D, bought new, 215k+ miles, donated to Purple Hearts veterans charity but I have parts for sale: http://www.peachparts.com/shopforum/mercedes-benz-cars-sale/296386-fs-1-owner-83-mb-300d-turbo-rebuild-parts.html

but the new one does the same too the field coil and the stator coil, diodes all nine of them all good I cant understand and the warning light seems to function good too no with alternator still and off with alternator turning and producing a current apparently too high

Hi,
Sorry about the 2X post I had no idea how this happened it's deleted now sorry

With your meter across the battery, on Volts DC, you should read 12.5 - 14VDC

If not, set your meter to Volts AC and you should have a reading of ~100mVAC.

If the VAC is too high, then look for a rectifying diode failure. If VAC is OK but the VDC is not correct, then the problem is with the voltage regulator.

Another note to mention is checking engine-chassis grounding and battery-chassis grounding. Poor grounding can reek havoc on alternators. Since you are using a transistorized, internal regulator, is there provision for a separate ground in the wiring?

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Sam

84 300SD 350K+ miles ( Blue Belle )

Hello,
Thanks I will do that and its just the 3 regular wires with the bosch alternator 2 red wires with a larger cross-section go to the solenoid in oder to have it connected with the battery and the other blue wire which connects on to the transistor and goes in series with a bulb (warning light) to0 a fuse and then connects to the ignition switch.

Thanks for the AC test idea and I will try that and post back!
Jeremy Brett