An E39 was presented to day with the battery constantly going flat. The owner had replaced the battery thinking that was the problem but it was not.
We investigated the fault and found a .92 amp drain, which is too much and will certainly drain the battery. After some investigation by Myron the fault was traced to the heater controller not shutting down properly.
The controllers are quite an expensive item so we re wired the heater directly to the ignition switch circuit so insuring the power was not getting to it once the key was removed. Therefore a cost effective repair was achieved for the customer.