Charge alternator.

Stephen Rigby

Senior Member
Mar 20, 2020
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Your Mercedes
E class 270d.
Good evening.
I have a 53plate e class 270d saloon.
The electric windows stop half way down while driving and sometimes the radio goes of briefly?
I've checked all the conections and cleaned and checked the fuses. In 3 fuse boxes.
Both the batterys are new.
If the engine is not running all works ok.
When I started it the fault appeared.
So I checked the charger alternator supply and it's to high at 16v. At the boot battery but 13v at the small under bonnet battery?
Before I buy a new alternator is there a external voltage regulator other than the one incorporated in the charge alternator.
I know the box in the boot is doing it job and protecting the system .
Just wonder if any one else as had a the same fault.
Thanks Steve


Senior Member
Sep 6, 2015
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Cambs UK
Your Mercedes
970 Panamera Turbo; W221 S500L AMG Line, C215 CL500, W251 R350L AMG Line, plus several more now gone
The alternator does have a diode pack yes, and at that age could easily be going u/s...

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