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Drain on Battery when car off???

mattman

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Howdy folks,

EDIT - SIMPLER QUESTION

Is it possible a faulty alternator or bad install can place a drain on the battery even when the car is off?

I have a 1 week old alt (output tested ok), 10 month old batt (tested fine) but there's a 1A drain on the batt when car is off.

This is in a CURSED WH V6... lol
 

vsl67

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A mate of mine use to have the same problem it turned out to be the glove box light switch was jammed on so check all of your light switches for a start
 

mattman

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Ah that is a good one :) and hard to see obviously lol.

Car is back at the auto elec anyway.

Found out the unit he put in is a Bosch and he said he knows about how the alt can drain the battery, but has never seen a new Bosch unit do it - ever.
 

delcowizzid

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if its got an emoboliser and stereo theres allways power drain
 

mattman

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Yeah but not so much that it flattens your battery overnight :) I think normal is anywhere up to about 0.2A, this was drawing just over 1A... ie... 5 times more than it should be.

After a quick charge from RACQ yesterday, it had 2 starts in it today before it needed to be jumpstarted. Fortunately those 2 starts got it to the radiator place then the auto elec...

Yes, I drive a cursed car :p
 

mattman

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Ok - here's one for you guys... car is all fixed now, $176 later (which I am happy with to have a car that should just work now).

The issue?

Well, the BCM drives a relay that drives the interior lighting, BCM had a fault where it wasn't cutting power to the relay when the car was shut off - even though no lights were on, the relay itself was causing enough of a drain to kill the battery. Sparky ripped out the relay and did a "magic wiring mod" so everything works 100% as intended, just no relay and no power drain. Said there's no need to replace BCM unless I want to be really anal about having everything as original (which for the sake of $500 I'm not).

Drain on battery gone from 1A to 20mA.... I'm happy :)
 

mrvdv

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good to see that you got it worked out
 
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