CarTalk.com Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

1995 bmw 318I electrical system draining problem

Hi, I have an electrical draining problem, with a little help maybe it can be solved, the car is a 1995 BMW 318I. The drain in the electrical system has been isolated to the following areas. These areas have the lowest draw. 1. Battery wires positive and negative. 2. Fusible Link and connecting wires. 3. B+ External start terminal and connection wires. 4. Distributor B+ and connection wires. 5. Ignition switch and connecting wires. 6. Front power distribution box. 7. Front head light wire harness. (both right and left front head light wire harness) Items that have been replaced more times than I would like to remember are the following, 1. Car battery. 2. Alternator. 3. Starter. The length of time between replacing each of these three items: Battery, Alternator, Starter, is less then one calender year. Just a side note. Before installing the car battery, the car battery is tested. It reads a full 12 volts. Upon installing the car battery it drops significantly. I think it my be a wire splice or soldered joint, in a wire somewhere, that is very hard to detect. Thanks for reading my New Discussion. Please feel free to respond. Take care and have a wonderful day!

A wire splice or solder joint can’t cause a battery drain problem by themselves. In order for a drain to occur a complete circuit has to to made for the current to flow and drain the battery. A starter can’t normally cause a battery drain because it isn’t connected to the battery until the starter solenoid connects it to the battery. A faulty alternator can cause a battery drain. When looking for this type of trouble a common thing to do is pull fuses one at a time while monitoring the battery current to see if the current drops to a normal amount. This would mean the circuit with the trouble has been disconnected when the fuse was pulled out. Here is a link that can help out.

http://www.aa1car.com/library/battery_runs_down.htm

This might be helpful also in addition to Cougar’s link.