Rolls-Royce and Bentley Forums banner
1 - 6 of 6 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter · #1 ·
I have a 2002 Arnage black label and have had it for several years. I have always had problems with he car holding charge. These are some of the things I have tried;

Replaced both batteries for new ones several times.

Trickled charged the car when not in use.

Tested the alternator.

Had a damaged earth cable replaced that went from the transmission to the chassis.

The car always seems slow to turn over.

The car can stand for several hours (not charging) and will start up. I can drive it a mile to the shop and it wont start up. I have to jump it off a third battery in the boot.

What else should I be checking? It seems as though both batteries drain but as I understand both should be independent until the ignition is on. Therefore a drain on the aux battery shouldn't interfere with the engine starting battery?

Many thanks
 

·
Registered
Joined
·
2 Posts
Discussion Starter · #4 ·
Thank you, a friend of mine that is an auto electrician is coming to see the car this evening.
Yes, the car has an aftermarket head unit, I will mention this to him.

If anything like the Mercedes (I am a little more familiar with) that runs two batteries, Is there a control module that links the two batteries? These are known on the Mercedes to cause problems.
 

·
Registered
Joined
·
4,278 Posts
Use a clamp-on amp meter or inline amp meter on the positive side of each battery. With a helper, remove each fuse independently and look for an amperage drop. Do this for each battery. One battery, usually the smaller one, is for starting, and the other for everything else. You should be able to isolate the circuit for further investigation.
 
1 - 6 of 6 Posts
Top