Parasitic Power Draw

02V70 · Post by **02V70** » 26 Mar 2022, 13:51

I was told that my volvo had a parasitic power draw, and the batter needed to be unplugged when the car was off. I did the test where I latch all the doors (this makes the car think the doors are closed when they are actually not) locked the car, and waited an hour. I then put a multimeter on each of the fuse terminals (without taking the fuse off) This video explains it. I the multimeter found 0.3 mv of current on Fuses number #27 (Front Door Modules) and #32 (Central Electronic Module: -ECPS, -Courtesy Lamps, -Glove Box lamp). Using this chart those circuits would be drawing 63mA and 39mA respectively. Is this enough current to cause a battery to drain? Or is this normal.

As I was typing this and the car has been sitting in the same state with the doors locked (but open) for about two hours. All the orange lights started flashing, and it was making a siren noise that seemed quite a bit quieter than a normal car alarm. Could this be the cause of the power draw? And it would not be noticed because the battery would be dead by the time the owner came back? Or would this be a result of the "fake" door closing and locking?

Edit: I talked to my dad, and he said that the siren never went off when he left the battery plugged in, and it drained overnight.

Post by **abscate** » 26 Mar 2022, 15:45

You need to measure amperage in series on each circuit to assess drains. The best place to do this is at the negative battery terminal.

50 mA or less is good

It is a bit tricky on P2 cars as they can tske 10-30 minutes to sleep

02V70 · Post by **02V70** » 26 Mar 2022, 15:55

I did that, and it said 0.1A or 100mA after 5 minutes. I connected a multimeter to the battey post, and the negative cable. I will try to make the test leads stay connected, and do the test again, but for 30 min. Since the power draw is only twice what is normal, would that cause the battery to drain overnight?

02V70 · Post by **02V70** » 26 Mar 2022, 17:21

After 45 Min it is 0.09A.

Post by **abscate** » 27 Mar 2022, 05:51

100 mA draw

24 hours * 0.100 Amp,is a 2.4 amp hour draw

Typical battery is up amp hours, so that would draw battery down 50% in three weeks or so.

If your battery is weak, thst could kill it in a week, but not overnight

02V70 · Post by **02V70** » 27 Mar 2022, 17:36

I left it plugged in overnight, and the battery did not die.