I have w124 which I have long time problem on either the battery or the alternator. I upgraded the alternator into a 90amps capacity and good that it is working fine. However, there comes a time that my battery is getting low charging due to low rpm when caught on heavy traffic causing the battery to drain.Will anyone have experience installing a dual battery as W211 set-up?

 

Hi,

If indeed you are using more power than your alternator is producing ...and I'm NOT SURE that on balance this is a correct statement...your solution is to fit a smaller pulley at the alternator.

Either you must have a lot of "optional" electrical load on ( headlamps, heated seats, ICE etc), you must spend a very long time in very heavy traffic or your charging circuit is not working correctly.
Of course another possibility is that "drain" occurs overnight with some consumers being left on or not shutting down properly.

A second battery is unlikely to resolve your problem.

Stuart

 

Thank you Stuart. However, I already made a smaller pulley and still having problem. I still remember that original set-up of this is without standard aircon. When I retro fitted with original set-up now it started the problem.

Anyway, thank you for your concern.

Cheers