TheSamba.com :: View topic - Testing for parasitic draw on my 2013 Outback

Sat Jan 29, 2022 4:45 pm

Hoping someone can help here-
I am trying to test for a parasitic draw on my 2013 Outback. My car has the keyless push start ignition, and for the past month or so every so often the car has initially failed to start when I press the button the first time. I thought it was just because of the cold weather, as removing the "key" from the fob and rubbing it with my hands to warm it up seemed to solve the issue. I also had been just keeping the fob in the car all the time, so I started carrying it with me in my pocket to keep it warm, and it seemed to work until yesterday when i got in the car to leave work, it wouldn't start again. It took 3-4 times of trying before it started.
I was wondering if it was battery related. The battery has a manufacture date of 7/21 so I don't think age is the issue. So I decided to test for a parasitic draw. The problem is, even waiting an hour after disconnecting the battery for systems to go to sleep, it appears I am getting a reading of 350 milliamps. (I selected the "Amp" setting on the meter which is 5 amps, and the display reads "0.35" which I take to mean 350 milliamps.
If this is correct, then how long should I wait before knowing for sure that it is a parasitic draw and not just a system staying awake?
TIA for any assistance.

Sat Jan 29, 2022 6:25 pm

Unhook the ground. Put an ammeter between the ground and the battery neg terminal. If the draw is more than Subaru states for their ECU ( assuming your running a subie ECU) start unplugging fixes until you see a change in the current draw.

Sat Jan 29, 2022 6:29 pm

350 mA is way too much, that will draw down a group 24 almost 10% per day.

It should be about 1/10 of that

Sat Jan 29, 2022 6:35 pm

adventurebob wrote: Unhook the ground. Put an ammeter between the ground and the battery neg terminal. If the draw is more than Subaru states for their ECU ( assuming your running a subie ECU) start unplugging fixes until you see a change in the current draw.

That is exactly how I connected the meter- unhooked the negative cable, waited an hour, then connected the multimeter inline between the negative battery cable and the negative battery terminal. I tried the 200 milliamp setting first and got the "1" off to the left side of the display which I believe means "out of range" so then I switched to the 5 amp setting, and saw .35 on the meter- I take it this does in fact mean 350 milliamps? Just want to be 100% sure, and also my original question still pertains- how long to wait before I am sure it is a parasitic draw and not just some systems still on?

Sat Jan 29, 2022 7:13 pm

update- folks on the Subaru forum pointed out that disconnecting then reconnecting the meter inline to test was "waking" the battery up and bringing a few systems online, thus the high amp rating. Leaving the meter connected inline for about 5-10 minutes now shows 10-15 milliamp rating, so I guess everything is good with the battery.

However, it was also pointed out that the Group 25 550 CCA OEM batteries Subaru put in these was very low, and suggested I try a Group 34 800 CCA battery instead, which may solve the hard start problem.

Mon Jan 31, 2022 9:32 am

If you are going to continue looking for parasitic draw, consider doing it one circuit at a time to narrow it down some....

Go to the fuse block & pull 1 fuse at a time. Place your amp meter in series, right where the fuse was. It doesn't even care which direction you put it... current is current. When you find the one leaking an objectionable amount of current, you have found the guilty circuit & just need to find the fault.

My last experience with this issue found a failed light switch on the passenger side vanity light. Even with the sun visor tucked away and the light cover closed... the light was still on, but couldn't be seen.

Good luck