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Discussion Starter · #1 ·
My 2001 325Ci coupe was drawing 120mA. Eventually I narrowed it down to two sources:
  1. The engine fan (Fuse 37) was drawing 60mA at all times. I understand this is a common problem.
  2. The Dice iPod interface (installed by the previous owner) was drawing 35mA at all times, even with no iPod installed. It's model I-BMW-T/5V.
I hope this information is helpful.
 

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E30M3 Race F10 535 R1150Rt M Coupe
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Yes both common.
When we chase after any parasitic draw, one of the first things we look for is any aftermarket interfaces installed. Often tucked under the console when the PO places it up for sale.
 

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POINT OF ORDER
Did you open all doors and the trunk lid and hood, then wait 15 - 20 minutes for the car to turn itself off?

You could close the doors and lock the car and it would turn off immediately, but it's hard to check stuff when the car is locked, and when you open anything it wakes up, pretty much killing the test you are doing. The car stays awake for 16 minutes until it decides that no other change in any load means that the doors being open is implausible, and it shuts off. If the car is off and you open a door, then it wakes up and the parasitic drains begin anew. Open everything you can and walk away. Come back in 20 minutes and see what the meter says. Do not open or close any door or trunk/hood while you are looking for the source of the drain.

I'm having trouble with the decimal point this morning, but assuming a 640 amp hour battery, the fan draw of 60mA should take more than 10,000 hours to kill the battery, this is more than 440 days.
 

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Discussion Starter · #6 ·
POINT OF ORDER
Did you open all doors and the trunk lid and hood, then wait 15 - 20 minutes for the car to turn itself off?
I opened the trunk (so I could check the battery) and the passenger's door (so I could check the fuses), then "closed" both by closing their latches with the screwdriver in the toolkit. The car thought they were closed, even though they were physically open. I also disconnected the switch from the glovebox light so I could open the glovebox to access the fuses.
I'm having trouble with the decimal point this morning, but assuming a 640 amp hour battery, the fan draw of 60mA should take more than 10,000 hours to kill the battery, this is more than 440 days.
80 Ah is more typical for a car battery. With a total draw of 120mA, that's 667 hours or 28 days. When the battery was new, it would barely last two weeks at 120mA, but that's because the E46 seems to have a crank lockout on a low battery - it won't even try to crank if the battery is below 12V. Now that the battery has been subject to that constant drain (even though I use a charger every couple of days) it barely lasts 2 days. Of course that's much longer now that I found the drains. I just got a replacement fan in that I'm about to install. I'll see how that goes.
 

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I opened the trunk (so I could check the battery) and the passenger's door (so I could check the fuses), then "closed" both by closing their latches with the screwdriver in the toolkit. The car thought they were closed, even though they were physically open. I also disconnected the switch from the glovebox light so I could open the glovebox to access the fuses.80 Ah is more typical for a car battery. With a total draw of 120mA, that's 667 hours or 28 days. When the battery was new, it would barely last two weeks at 120mA, but that's because the E46 seems to have a crank lockout on a low battery - it won't even try to crank if the battery is below 12V. Now that the battery has been subject to that constant drain (even though I use a charger every couple of days) it barely lasts 2 days. Of course that's much longer now that I found the drains. I just got a replacement fan in that I'm about to install. I'll see how that goes.

I got my wires crossed. 660 is the cold cranking amps, and 64 is the amp hours. My bad, but the math is right and you seem to already know that.

You could open everything and walk away for 20 minutes and the car will time out, but what you did should work too.
 
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