Battery keeps draining every few days ugh

I measure for AC voltage across the battery terminals:

Forester: 22mVAC

Legacy (reference): 48mVAC

I don’t have an o-scope, so no way to see it’s true waveform, nor the DC.
 
Snagglefoot said:
To properly test for a parasitic draw, use a multimeter that has clip-on connectors. (you can get clip-on connectors from Amazon). Disconnect the negative cable and clip the negative from the multi-meter to it. Clip the positive lead from the multi-meter to the positive battery cable that is still connected to the battery. Have your multi-meter set to AMPS, not Milliamps. (Don't burn out the fuse of your multi-meter). Now, with the doors closed and all lights off, watch the amperage. With the electronics active it might be a few amps. Let the car electronics "go to sleep" which will take 10-20 minutes. You'll see the amperage drop off. It everything was OK, there should be 40-50 milliamps of draw to power the clock and alarm system. If after 30 minutes, you still have a big draw, start pulling fuses one by one.
Click to expand...
I need to correct one item. You clip the positive lead from the multimeter to the negative terminal., not the the positive battery cable. That way the multimeter is in series with the battery. If your clip is small you can use a single clamp from a set of battery cables attached to the negative terminal and clip onto that.
 
Snagglefoot said:
I need to correct one item. You clip the positive lead from the multimeter to the negative terminal., not the the positive battery cable. That way the multimeter is in series with the battery. If your clip is small you can use a single clamp from a set of battery cables attached to the negative terminal and clip onto that.
Click to expand...

I just held the leads in place. I searched my Amazon orders and I DID apparently buy alligator leads. I just need to find them for long-term trouble-shooting. With the alligator leads hooked up I’ll be able to just hang out in the garage and listen for Fluke (DMM) beeps when a new high current draw is detected.
 
I found my alligator clamp leads and they’re now hooked up to measure parasitic drain. My Fluke 117 is set for max. I’ll monitor every so often until I go to bed tonight. I’ll leave it hooked up while I sleep, as well. That should tell me the average draw through the night, as well as max draw.
 
Just got back from work:

Ave/Max no higher than before (max actually 171mA this time)

Battery voltage (sitting four days): 12.24

Interesting data: I have all interior lights replaced with Diode Dynamics brighter LED’s.

All interior lights on + hatch open + front door puddle lights on: 800mA

All lights off + hatch open: 400mA for > 10 min (didn’t check longer

hatch shut, no loads, let sit several minutes: normal 35mA

This does prove that leaving the hatch open will drain the battery, even if the lights are all off. I’m going to let the battery sit over night, disconnected from everything, to see if battery voltage lowers from 12.24VDC, although I think we can say at this point it’s not the battery. Still no smoking gun...
 
I am not familiar with the Subaru in detail. But on the Honda CR-V owners forum, there was a post of someone who had a vehicle that the battery was draining on. One day as they walked towards the vehicle with the key-fob they heard the doors unlock before they touched a front door handle. ( With the Honda you have to have the fob with you, and touch the inside of a front door handle, and only when you touch the inside of a front door handle it will unlock. ) Because it unlocked without them touching a front door handle, they figured out that one of the front door handles was acting like someone was touching it when no one was. It turned out to be the front passengers door handle had gone bad.

BTW, divide and conquer would of found this, though again it would of taken time.
 
Battery (open-circuit) voltage came back up to 12.38 from 12.24 over night. I did measure the voltage soon after messing with everything from the doors to the rear gate, so that checks.

@JimPghPA This 14 Forester’s keyless entry is identical.

It‘s hard to half-split the problem when it won’t even present itself for multiple days. The only thing I have found is that it’s true that the hatch being open causes a pretty significant draw and would explain my results, if it would just present itself.
 
gathermewool said:
Battery (open-circuit) voltage came back up to 12.38 from 12.24 over night. I did measure the voltage soon after messing with everything from the doors to the rear gate, so that checks.

@JimPghPA This 14 Forester’s keyless entry is identical.

It‘s hard to half-split the problem when it won’t even present itself for multiple days. The only thing I have found is that it’s true that the hatch being open causes a pretty significant draw and would explain my results, if it would just present itself.
Click to expand...
How do you eat an elephant?
































One bite at a time.
 
Been Better lately.. . Had a rough stretch for awhile about 3 months ago. And it lasted a bit there.

It has been nice feeling up to going to 3 large stores in a day. And able to do that and feel fairly good while doing that too.

Only had one rough day in the last 3 weeks. I crashed for about a day and a half.

Been rolling pretty good since.
 
bbhero said:
Been Better lately.. . Had a rough stretch for awhile about 3 months ago. And it lasted a bit there.

It has been nice feeling up to going to 3 large stores in a day. And able to do that and feel fairly good while doing that too.

Only had one rough day in the last 3 weeks. I crashed for about a day and a half.

Been rolling pretty good since.
Click to expand...

Excellent to hear. here’s hoping for nothing but good days for you going forward
 
Checked the voltage this afternoon and 11.95VDC. Charging currently. Car was driven a good amount Saturday, 10 miles or so yesterday and the day before. It should be driven enough to maintain the voltage around full.

Will perform another draw test tonight to see *** is going on.
 
gathermewool said:
Checked the voltage this afternoon and 11.95VDC. Charging currently. Car was driven a good amount Saturday, 10 miles or so yesterday and the day before. It should be driven enough to maintain the voltage around full.

Will perform another draw test tonight to see *** is going on.
Click to expand...
I had a bad habit of leaving my map light on or my trunk lid ajar in my garage. If I didn't drive for several days I might have a flat battery.

Since I replaced the dome, map lights and trunk lights with LED bulbs, no more issues.

I've still left the lights on. But the LEDs draw so much less that I've not been caught out by my own inattentiveness.

It usually happens when I'm on-call and have had a long day, followed by WFH or a weekend without driving...

If your issue is leaving lights on, perhaps replacing bulbs with their equivalent LEDs is a mitigation strategy.
 
javacontour said:
I had a bad habit of leaving my map light on or my trunk lid ajar in my garage. If I didn't drive for several days I might have a flat battery.

Since I replaced the dome, map lights and trunk lights with LED bulbs, no more issues.

I've still left the lights on. But the LEDs draw so much less that I've not been caught out by my own inattentiveness.

It usually happens when I'm on-call and have had a long day, followed by WFH or a weekend without driving...

If your issue is leaving lights on, perhaps replacing bulbs with their equivalent LEDs is a mitigation strategy.
Click to expand...

No lights on. This is a repeatable issue without any data pointing toward an excessive draw.

All lights have been LED for a long time.
 
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