1992 BMW 525

HI there,

Get a current draw test done, have an Amp meter placed between Battery Pos (+) and the terminal, (don't try and start the engine) with key out and doors closed check for current dray, if excessive start to pull fuses and fusible links one at a time to isolate the problem circuit, also disconnect the alternator as it may have a faulty diode beck feeding to the battery, start here,

Mark (mhpautos)