why is my altonator draining my battary power?

Greetings, Alternators don't typically drain battery power. If alternator is faulty it may not provide enough voltage to charge the battery. Why would you put a more powerful alternator? and without inspecting the vehicle it is impossible to tell if the wiring harness would need to be replaced or repairable if that is even the problem. You should take the car to another repair shop to have a second opinion. Expect to pay someone for diagnosis as someone will need to spend a considerable amount of time to troubleshoot this concern. Kind regards, Stephane Grabina BMW Excluservice 12224 Parklawn Drive Rockville, MD 20852 (301)231-5400 ext.1 www.bmwexcluservice.com

It sounds like u have a bad wire, check that the wires are Not lose, n if its not that i would replace some wires but make sure u know what you doing when checking n replacing. That should help.