E320 CDI W211 Battery Charging

[gruffalo]

Quick question to those who may know but I seem to have a faulty charging circuit on my old E class.

Battery charges up fine if I connect a battery charger directly to the battery in the boot but charging rate from the car when running is very slow and I have to charge the battery directly every couple of weeks.

13.8 volts read at the battery when the engine is running but the battery takes hours of driving to charge up properly.

If I connect my battery charger to the posts under the bonnet I get a similar issue, a very slow charge rate.

So in summary the battery charges well if the charger is connected directly but does not if charged either by the alternator or battery charger connected under the bonnet.

Any ideas?

[TarquinMX5]

Have you checked the simple stuff first, such as connections on battery terminals, earth etc. and how old is the battery?

[gruffalo]

TarquinMX5 said:

Have you checked the simple stuff first, such as connections on battery terminals, earth etc. and how old is the battery?

Yes checked all that and if I charge the battery directly all is well just short runs are slowly flattening the battery as the charge rate is too slow.

[THUNDER STORM]

Can only suggest that it may pay to have alternator checked by a auto electrician.

Ade

[Greenmantle]

This is due to the regulator on the alternator.
Google w211 regulator in you tube.
An Indian guy in the USA has a simple video.
Did mine on a 53 plate W211 270CDI about 10 years ago. £60 part from Hughes Beaconsfield.
Gosh - I miss that car.
Star Indy in Reading were going to lighten my wallet by £500.

PS Tayna Batteries in Wales is the place to go for batteries - Varta everytime.

[gruffalo]

Greenmantle said:

This is due to the regulator on the alternator.
Google w211 regulator in you tube.
An Indian guy in the USA has a simple video.
Did mine on a 53 plate W211 270CDI about 10 years ago. £60 part from Hughes Beaconsfield.
Gosh - I miss that car.
Star Indy in Reading were going to lighten my wallet by £500.

PS Tayna Batteries in Wales is the place to go for batteries - Varta everytime.

Thank you.