Parasitic battery drain

Finding a parasitic battery drain that drags the battery down over a 2 day period can be a tough job. But using a test plan will definitely make it easier.

This Fiat would bring the battery down below 10 volts in about 48 hours and was driving a car owner crazy. The problem was looked at under warranty by a dealer but they couldn’t find the answer.

FIAT parasitic battery drain

I started with a simple amp clamp over the main battery cables to get an idea of draw. It showed a steady 250mA drain. Doing some simple checks across the fuses with the Amp Hound I found a constant draw from the fuse feeding the body control module.

Connecting a scope in series gave me a much more accurate look at the current draw and I used the fuse test again inside the vehicle. Under the dash we had the remnants of a handsfree kit which was giving me 100mA draw. The rest of the draw, 150mA, was caused by a faulty Bluetooth module.

These were disconnected about a month ago and the car has been fine ever since. 

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