Batery Control Module

[woodysl]

R230, SL350 2003 model year. Battery continues to have a parasitic discharge problem. Usual checks have been carried out, e.g no courtesy lights being left on, new consumer battey fitted, BCM checked to confirm it is charging the battery after a 15 minute run, alarm siren/sytem disconnected with zero effect. I have seen reports that a faulty BCM can also lead to parasitic battery discharge over a period of time. Has anyone else heard of this problem? I am about to start the tedious task of pulling fuses and checking current draw using an ameter, but it would be handy to know beforehand if the BCM could be the cause of the problem. Also any other ideas would be gratefully received.

 

[woodysl]

Stranger still. Battery in engine compartment gave up the ghost without warning, the battery was about 8 or 9 years old. Checked with battery tester and showing poor CCA, pointing to a problem with the battery cells. New battery installed and no problems since, with drain of the big ancillaries battery in the boot. Any ideas why this has happened? Was the BCM trying to keep the starter battery fully charged leading to the ancillaries battery being undercharged?