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Location: Seattle, WA
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Current draw when engine off?

I drove three days ago in the day time. When I went to start the car this AM the battery was totally dead. The lights were not left on, the doors had been closed, everything electronic that I can see has been off. How can I test to see if something is pulling juice out of the battery when the car is off? And if there's a short, any ideas on how to find it?

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82 911SC Targa
Old 03-30-2016, 12:09 PM
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Try a search. Lots of threads on all aspects this subject here.
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Old 03-30-2016, 12:22 PM
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Get a mulitmeter, and set it to amps
Unhook the positive battery cable to the battery.
Place the Black needle on the positive cable.
Place the Red needle on the positive terminal of the battery.
If a voltage appears that means that there is a draw.

Last edited by pemz0r; 03-31-2016 at 05:46 PM..
Old 03-30-2016, 12:30 PM
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Thanks! There was a draw and I found the culprit - the glove box light was on (yes, I feel foolish, but I couldn't see this very easily in the daylight). I must have bumped it getting my sunglasses out (Targa owner).
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Old 03-30-2016, 01:02 PM
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Awesome!
Old 03-30-2016, 04:33 PM
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After a few days with bad/ hard starting, I installed a battery cutoff switch. So my draw is zero!!
Old 03-30-2016, 08:50 PM
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Glad you found the problem. Just to answer the question (I just went through this recently) I found on my SC that once I eliminated the parasitic draw the steady state use was 7-8 mA. Some people suggest anything higher than 30-50mA is something to investigate. That's a good rule of thumb.
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Old 03-31-2016, 01:49 AM
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Quote:
Originally Posted by pemz0r View Post
Get a mulitmeter, and set it to 200.
Unhook the positive battery cable to the battery.
Place the Black needle on the positive cable.
Place the Red needle on the positive terminal of the battery.
If a voltage appears that means that there is a draw.
that's not correct.

you have to measure AMPS.

it takes very very little current for a meter to measure voltage.

a test light works too. the brighter it is, the more current
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Old 03-31-2016, 02:38 AM
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you are correct. i meant amps not volts.

Old 03-31-2016, 05:45 PM
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