Q: Something is draining the juice out of the battery in my 2003 Diamante, and no one can find the source. I've replaced the battery three...

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Q: Something is draining the juice out of the battery in my 2003 Diamante, and no one can find the source. I’ve replaced the battery three times in two years. If I park the car more than a few days it won’t start.

A: Wow! You’ve certainly been through the wringer. The first step is to purchase and install a battery terminal quick disconnect (at Griotsgarage.com or locally). This $12 device attaches between one of the battery posts and the terminal attached to it. By simply turning a knob, you’ll be able to isolate the battery from the car overnight.

Within a week or so, you’ll discover for sure if the fault is (was) due to drain-down, or lies elsewhere, such as the charging system or battery itself. Isolating the battery overnight isn’t a good long-term fix, as you’ll continually lose the clock, radio stations, emissions monitors, and engine control learning/adjusting memories, in addition to being a tedious chore.

You can even attach an ammeter (a function of the inexpensive multimeter discussed a few weeks back) to each side of the disconnect device to display how much electrical current (measured in amps) the car is consuming. The suspect list is ample, but knowing the size of the drain and when it’s there are huge clues that can be followed up by removing fuses or unplugging components until all but the tiniest drain remains.

E-mail Brad Bergholdt at under-the-hood@juno.com