Mercedes-Benz Forum banner

1 - 5 of 5 Posts

·
Registered
1981 240D
Joined
·
133 Posts
Discussion Starter #1
My '82 240D battery died over the weekend.
Old battery is six years old.

I installed Bosch battery (49-850B) CCA @ 0F 850 Ca @ 32F 1000 RC min @ 25A 120 from Pepboys.

Voltage is measured at 12.76V before engine starts.
After engine starts, it reads 12.45V.

Isn't it supposed to be above 13V after engine starts as alternator supplies juicy current?
 

·
Registered
'89 300TE, '79 450SL, '01 ML320
Joined
·
1,051 Posts
Sounds like it's time for a voltage regulator, two screws in the back of the alternator, easy to change.



Fish
 

·
Premium Member
Joined
·
496 Posts
Check to make sure when you turn the key on, your dash has the battery light on in the lower left of the gauge cluster. If that bulb is burned out, your system will not charge. If that comes on and then goes away (which I think it should stay on if it's not charging!) than I would also look toward the voltage regulator/alternator.

Dave aka Ghan
 

·
Premium Member
99 SLK230 Kompressor, 5 Speed Manual
Joined
·
1,117 Posts
Yes, when running, a properly operating charging system should cause the battery voltage to be about 13.5 to 14.5 Volts.

As indicated above, make sure the charge indicator light is good, by checking with key on engine off. If it is good, then use a digital voltmeter to check voltage at the output of the voltage regulator on the alternator. If you have voltage there, check wiring between alternator and battery, actually physically going through solenoid post as I recall.

It is quick and easy to pull the voltage regulator from the alternator while leaving alternator in place. If brushes are worn replace it. There are third party brands available cheap that are of good quality.

If this doesn't get you any further, post back here and we will help you work through it.
 
1 - 5 of 5 Posts
Top