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Battery Drain... How many amps?

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Old 03-06-2010, 06:33 PM
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Jim Chambers
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Default Battery Drain... How many amps?

I have searched the "drain" topic but don't find an answer.

'90 GT-With interior lights on (door and hatch open) I measure a draw of 4.69 amps.
Then I pull fuse 25 (interior lights) and the draw is .89 (pass footwell light is still on).
After pulling many fuses I learn that #26 turns off the footwell light.
Now I have a draw of .18 amps. Is this too much? If so, how many amps does a resting car draw?
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Old 03-06-2010, 06:57 PM
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Alan
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it should be less than 25mA - that is 0.025A

However your test method is not good... you need to make sure the car thinks the doors and hatch are shut.. otherwise even with the bulb fuses out there may be relays on - a relay coil is approx 150mA alone...


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Old 03-06-2010, 07:01 PM
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John Speake

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The extra drain is probably your alarm system ? (I don't think Alan icluded that)

So your drain is approx 6 hours for 1 Ampere/hour. You battery is 60A/H or so, so should last for 360 hours, or 15 days which sounds typical.
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Old 03-06-2010, 07:13 PM
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Alan
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John - even with the alarm - 25mA

180 mA is about 150mA too high...

Its not a disaster and probably isn't even real - but if it is real it indicates a problem...

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Old 03-06-2010, 07:28 PM
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Jim Chambers
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Thanks Alan. First, I must correct my first post: fuse 22 (left seat power) turns off the footwell light, go figure. I don't think I have an alarm. Or is it standard? I don't have a long key, but I only got one with the car. How can I check? Lock door with window open, then open door from inside? That sets off alarm in some cars.

How do I make the car think all is shut and then test? Close hatch, crawl in through the front and shut door, then wait until the interior lights go off? Or does the relay draw even after the lights go out? (BTW, all interior lights and door red lights are working properly) At that point I then test amps at the ground, hoping for .025A or less?
If I have more, repeat the process after pulling one fuse at a time (times 42!)?

I got it, put wife if back with meter while I pull one fuse at a time!
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Old 03-06-2010, 10:33 PM
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Use long test leads so you can see the meter while sitting in the passenger seat...
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Old 03-06-2010, 10:37 PM
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You could connect the meter then close the hatch and read it through the window once the lights go off.
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