W124 300e Battery light on with engine running - replace alternator or voltage regulator

[MercedesintheBlood]

Hello

W124 300e battery light is on with car running. Battery is new.

Getting 12 v on battery terminal with car running. Should be 13-14 v.

replace alternator or replace voltage regulator first ?



Thanks

 

[Ted]

I would always replace the voltage reg first. It’s much cheaper, easier, and you get a new set of brushes as part of the regulator.
Check you have battery voltage to the thick wire on the alternator.

The voltage should be around 14-14.3 with the engine running

 

[optimusprime]

Voltage regulator is a 2 screw fix .make sure the brushes are on the slip ring on fitting it .Remove battery lead first make sure you have the radio code . Earth lead off first and refit earth lead last.