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Still had an issue afterwards. Yes I have an amp clamp. Troubleshooting electrical issues was what I did for a career for over 40 years. I specialized in fixing phantom issues and history codes. I could not get my dealer to troubleshoot the cause of all the history codes. I had to be cautious because I did not want to void the warranty. The light bulb is still out of the socket. I'm upgrading to a 2022 next month. My lease is up cheaper to get a new one
Would you mind testing with the light out, clamp around the battery's negative cable, and see if the power drops in 20 minutes? And do the same with the light?

Also, to confirm, you did have, or did not have, the liftgate controller replaced?
 

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I've been at the dealership many times because the battery in my Subaru keeps dying on me. They can't find the root of the problem. Plus they told me it's totally normal that it does that. I might be a woman but I'm no idiot. Here's what they told me to do:
1. Drive it every day for an hour or so.(With the price of gas today, that's not going to happen plus I don't want to put in too many km on my vehicle as it will need to last me a long time as I can't afford another one)
2. Buy a battery tender and plug it(I do not have an outlet at my house to plug it into) and this will not work if I go to the airport and need to leave my vehicle there for a few days or when I go camping in the woods with my grandkids as there are no electricity or cell phone services there.
3. Bring tools and unhook the battery - I don't have a clue how to do this
4. Call a tow truck to have it boosted every time - This is too expensive

I'm beyond frustrated as I've been on foot for many weeks now and I just talked to them again today and the guy at service told me that it's totally normal that it does that and that they wasted many hours on my vehicle and they won't do anything else for me. It's hard to believe that I spent close to $70,000 for this vehicle and I'm on foot. I called Subaru Canada twice, they were supposed to get back to me but never did. I know there has been many class action law suit going on for this issue. I read every comments in this forum and on the internet but nothing seem to fix the problem. It's my first Subaru and bought it before reading about how much trouble they are and the lack of service you get when you have problems with your Subaru. Can someone help me?
I was having similar battery problems with my 2020 Ascent: the battery kept dying.
From reading this forum I realized this was quite common: the factory batteries were garbage.

Living an hour and a half from the dealership, and not wanting to waste a day just to end up with another factory battery, I went ahead and bought a replacement. I got an Odyssey Performance series, due to Consumer Reports high rating, and installed it myself. (No battery problems since).

Then--- also prompted by something I remembered reading on here--- I emailed Subaru USA Customer Service, explained my situation, and asked if they could reimburse me for the new battery.

And lo and behold! they did! I emailed them a copy of my receipt, and a week of so later got a check for the $246 and change the Odyssey had cost me.

i ended up with a much better battery at no cost, and without having to waste a lot of time at the dealer.

You may want to consider giving it a try....
 

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The battery on my brand new 2019 was dead when I picked it up from the dealership (trust me, I did not appreciate the look I got when I told the service department. It may have been my first car with a push start ignition but I've been driving over 30 years, I know what I dead battery is). Once the pandemic hit, I was rarely driving and I had to jump start it EVERY SINGLE TIME I wanted to drive. I bought one of those fabulous lithium jump starters and traveled with it. I've had all of the recalls for my vehicle serviced and the last time it was in for service, they told me my battery was dead so they charged it fully. Happily, my car never had issues after that. I did have the controller recall service performed prior to that appointment, but I suspect they didn't fully charge the battery at that time (why would they?) and my continued issues were a combination of the known batteries issues/an underpowered battery and infrequent short trips. Anyway, much luck to you, there are a lot of good suggestions in this thread. I just wanted to share my experience with you in commiseration.
 

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Purchase a lithium battery jump such as this one AmazonSmile: Imazing Portable Car Jump Starter - 2000A Peak 18000mAH (Up to 8.0L Gas or 7.5L Diesel Engine) 12V Auto Battery Booster Portable Power Pack with Indicator Jumper Cables, QC 3.0 and LED Light : Automotive . We have one of these in every vehicle we own, and they are quite useful in the case that you do accidently run the battery down while camping, which we have done, or have some similar misadventure. These are small enough to stash under a seat or with the spare tire.
Anyone who carries a lithium jump starter should keep it in the cabin, accessible but secured in place. If it's under the cargo compartment and the battery dies you won't be able to open the rear gate easily.
 

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Anyone who carries a lithium jump starter should keep it in the cabin, accessible but secured in place. If it's under the cargo compartment and the battery dies you won't be able to open the rear gate easily.
That's an interesting thought. I wonder, if in the "normal" dead battery scenario, there would be enough current available to pop the hatch since there usually is enough to turn on the lights and radio so that victims think it is not the dead batttery causing their car not to start. I do not want to do that experiment.
 

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Anyone who carries a lithium jump starter should keep it in the cabin, accessible but secured in place. If it's under the cargo compartment and the battery dies you won't be able to open the rear gate easily.
Agree. I keep mine under the driver's seat.
 

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That's odd, but not odd at the same time. Do you have access to a clamp on DC ammeter? And, from what you're describing, I gather you never had your liftgate controller replaced?
Robert, You're going down the right path on the root cause of the problem described. I had my battery drained to zero twice and the third time, the battery was dead after about a year and 10K miles. I had read about the liftgate controller causing parasitic voltage drain and when the dealer was only going to replace the dead battery, I told them I wanted them to perform the TSB to check for parasitic voltage drain. They resisted a bit, but went ahead and did the check and, lo and behold, found the voltage drain about 5X above the max spec. They replaced the liftgate controller as well. The problem is largely resolved now, although, I had one further incident with the battery draining when I had the liftgate open for about a half hour while loading baggage for a vacation trip.

The lesson there is that even with the liftgate controller replaced, you still can not leave the lift gate open for any length of time over about 10 minutes. I also take care not to leave any phones plugged in charging after the vehicle is turned off, as they also seem to contribute to voltage drain high enough to affect the battery if left charging for several hours.

I've learned to live with the inadequacies and design flaws in the charging system on the Ascent, but due to my experience with this marginal to inadequate charging system design, this will be my last purchase of a Subaru.
 

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That's an interesting thought. I wonder, if in the "normal" dead battery scenario, there would be enough current available to pop the hatch since there usually is enough to turn on the lights and radio so that victims think it is not the dead batttery causing their car not to start. I do not want to do that experiment.
I've done the experiment. The answer is...it depends.
 

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Robert, You're going down the right path on the root cause of the problem described. I had my battery drained to zero twice and the third time, the battery was dead after about a year and 10K miles. I had read about the liftgate controller causing parasitic voltage drain and when the dealer was only going to replace the dead battery, I told them I wanted them to perform the TSB to check for parasitic voltage drain. They resisted a bit, but went ahead and did the check and, lo and behold, found the voltage drain about 5X above the max spec. They replaced the liftgate controller as well. The problem is largely resolved now, although, I had one further incident with the battery draining when I had the liftgate open for about a half hour while loading baggage for a vacation trip.

The lesson there is that even with the liftgate controller replaced, you still can not leave the lift gate open for any length of time over about 10 minutes. I also take care not to leave any phones plugged in charging after the vehicle is turned off, as they also seem to contribute to voltage drain high enough to affect the battery if left charging for several hours.

I've learned to live with the inadequacies and design flaws in the charging system on the Ascent, but due to my experience with this marginal to inadequate charging system design, this will be my last purchase of a Subaru.
Yep!!! First, there are a half dozen liftgate controller versions. The fully corrected "works with all trims and variants" version will stop causing the current draw in exactly 20 minutes.

BUT, assuming you have a properly working controller (newer version), problem number 2: if you open a door, that 20 minute timeout restarts. If you or lock/unlock a door, I believe the 20 minute timeout restarts again as well. The 20 minute timeout restarts even if the original one completed.

Otherwise, you can leave the liftgate up "forever" (with one of the updated controllers installed).

By the way, the liftgate controller is NOT the current draw source.
Many dealership techs don't even understand that. The controller keeps pinging the ECU, keeping the ECU awake, causing the ECU to draw power. So, what many of them don't understand is that the liftgate controller is the cause, but not the source, of the current draw. If they go through all the training material and electrical diagnostics stuff, they'll figure it out too.

Problem #3, totally unrelated to the liftgate, is the car waking up when you walk within range of the side FOB sensors with the FOB on you. In some cases, you can even catch the head unit pre-booting.

Regardless, I am sorry to hear of your experiences and battles with getting it fixed.

You can verify you've got a controller that properly times out its communication with the ECU by clamping after the battery (I suggest the negative cable bundle, because a DC clamp meter fits over it easier), opening the liftgate, watching the power draw spike, and counting down 20 minute without opening a door, or locking/unlocking a door. In exactly 20 minutes, current draw should drop to near nothing, and the cargo light (assuming the switch is in the on position) should turn off. If current draw remains the same, the liftgate controller is NOT the one that properly enforces the 20 minute timeout.

Oh, and that above is the "really simple version". There's the Body Integration Unit that sits in the middle, handling all this stuff (for instance, pretty sure it's what wakes up the liftgate controller when a side door is opened).

And, in some few cases, it's the BIU that's the cause of parasitic draw (the cases where it's not related to the liftgate controller activity).

AND FINALLY...
Any of you who've had an OEM battery killed a few times because of this have a big chance of having a battery that's not going to hold a charge under load as it should. They're not designed for repeated deep discharge (or ANY deep discharges, for that matter). Even fixing the current draw won't solve the overall problem when a battery is damaged but not replaced.
 
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