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Discussion Starter #1
Drove it Thursday, then yesterday only opened the rear hatch to get something out, and then closed it. Today went to to start and battery was drained. No lights left on. Charged up the battery and took it for a spin. When I stopped I could not open hatch with my hand. Was able to get it to open when I got back home. Wonder if the hatch didn’t seal all the way or something causing the battery to drain
 

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One person had their rear cargo tray preventing the rear hatch from closing all the way so maybe the hatch had this issue but when you lock the car it should notify you that not all the doors are closed by giving a different set of beeps.

It is known that the 620CCA batteries are failure prone, so it could be that. Which battery do you have installed? Take and share a photo of the top of the battery if you don't know.
 

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'17 OB Limited 3.6R
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- Have dealer check for a dead cell (maybe a dud battery)

- Even though a 2021 model, the computer may need the service bulletin addressed update for the battery charging parameters at low speed/stop-go driving. Our '18 just had this done after we drove it a bit for a day, parked for a few days, attempted to start with zero signs of life. Meter showed battery pumping out a mean 0.02 volts!


Just a couple thoughts. If battery shows a problem (or charging system as a whole), dealer can warranty the situation.
 

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2020 OB Limited, Titanium & Magnetite Grays
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One person had their rear cargo tray preventing the rear hatch from closing all the way so maybe the hatch had this issue but when you lock the car it should notify you that not all the doors are closed by giving a different set of beeps.

It is known that the 620CCA batteries are failure prone, so it could be that. Which battery do you have installed? Take and share a photo of the top of the battery if you don't know.
A survey/other provided info that only 620CCA batteries were delivered on 2020s. After March builds there were no failures reported. 640CCA were only reported as installed as replacements for the failed batteries. For the record, I recently had the new software installed and afterwards the software allows the battery to discharge to 11.7V during ASS.
 

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For the record, I recently had the new software installed and afterwards the software allows the battery to discharge to 11.7V during ASS.
On the surface it appears that the 'smart charging algorithm' is faulty - is there any other explanation for this? I haven't checked voltages post 380 but like @ArF193 I saw voltage readings as low as 11.9 while the car was running on 504.
 

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2020 Outback Limited
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2020 limited here on 504 from the factory with a 620 battery. I installed a voltmeter in the cabin that's always on (switchable). When the car is running, it's always at 14.3V no matter the conditions. It gets as low as 10.1 during starting.
 

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2020 OB Limited, Titanium & Magnetite Grays
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When stopped and ASS is active, how low does the voltage drop before the engine restarts? When driving, I have found using Factory Mode to display voltage a little easier to view and I think the display shows voltage the vehicle is using to make decisions.
 

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2020 Outback Limited
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I have the ASS Eliminator, so no data point there. I could turn it on sometime and check it though, if I can remember to do it.
 

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When stopped and ASS is active, how low does the voltage drop before the engine restarts?
I just tried it, the engine restarted at 11.8V.
I also tried idling with headlights on, heater fan on highest setting, and all 4 seat heaters on, idling voltage was still solid at 14.3V, so charging system seems fine.
 

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I just tried it, the engine restarted at 11.8V.
I also tried idling with headlights on, heater fan on highest setting, and all 4 seat heaters on, idling voltage was still solid at 14.3V, so charging system seems fine.
These smart charging algorithms give full voltage when there's a load but decrease voltage under low load, so with headlights off, heater fan off, etc. you'll potentially see the low voltages under those conditions.
 

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I have the ASS Eliminator, so no data point there. I could turn it on sometime and check it though, if I can remember to do it.
I think that valuable information could be gathered by someone running the ASS eliminator. If they would install a conventional flooded lead acid battery which may rid the problems of the LN2 stock battery. If the battery has no issues then a number of owners would be really happy and have nothing to post.

.
 

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These smart charging algorithms give full voltage when there's a load but decrease voltage under low load, so with headlights off, heater fan off, etc. you'll potentially see the low voltages under those conditions.
Interesting. I'll try to test it out sometime.
 

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I just tried it, the engine restarted at 11.8V.
I also tried idling with headlights on, heater fan on highest setting, and all 4 seat heaters on, idling voltage was still solid at 14.3V, so charging system seems fine.
I am surprised it even starts at this voltage, but I have seen the same with our Outback.
The battery is dangerously low at 11.8V.
 

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Discussion Starter #14
One person had their rear cargo tray preventing the rear hatch from closing all the way so maybe the hatch had this issue but when you lock the car it should notify you that not all the doors are closed by giving a different set of beeps.

It is known that the 620CCA batteries are failure prone, so it could be that. Which battery do you have installed? Take and share a photo of the top of the battery if you don't know.
battery is to low to start again today, looked and it is a 620cca battery. Going in for service on Monday going to see what they say about it.
 

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2020 OB Limited, Titanium & Magnetite Grays
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The sum of the failures has only the 620CCA batteries. From the survey, the 640CCA are only used as dealer replacements and so far there are no reported failures. The no failures of the 640s may be due to the low number of installations.
 

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2020 Outback Touring XT, in Crystal White Pearl
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My own theory is that the replacement "640CCA" battery is essentially the same as the 620CCA battery, and just stickered differently to make it more obvious that the battery is a replacement, and not the original..... Also, that the problems that occurred in some fairly early-production cars with the 620CCA battery were limited to a small number of batteries, and that quality control improvements were made in the production of the subsequent 620CCA batteries (as well as the 640CCA batteries used as replacements).

But these are just my own theories / speculations....
 

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My own theory is that the replacement "640CCA" battery is essentially the same as the 620CCA battery, and just stickered differently to make it more obvious that the battery is a replacement, and not the original..... Also, that the problems that occurred in some fairly early-production cars with the 620CCA battery were limited to a small number of batteries, and that quality control improvements were made in the production of the subsequent 620CCA batteries (as well as the 640CCA batteries used as replacements).

But these are just my own theories / speculations....
I like it when someone says something that gives me pause. Certainly plausible that there have been running changes/improvements to the battery if the 2021 guys were having a better experience. I'm a cynic when it comes to quality and my bias is to expect quality to decline instead of improve, when a parts supplier is recently acquired by a private equity firm.

edit: I'm talking about Johnson Controls being acquired by Brookfield Partners, not Subaru.


 

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I like it when someone says something that gives me pause. Certainly plausible that there have been running changes/improvements to the battery if the 2021 guys were having a better experience. I'm a cynic when it comes to quality and my bias is to expect quality to decline instead of improve, when a parts supplier is recently acquired by a private equity firm.
Interesting views from both. Some time ago, I found that the Japanese companies I had relationships with remained decuples of Deming and followed continuous process improvement methods. I yield to the possibility this may not be true in all cases, but would be surprised if it were not part of the Subaru culture. With this position in mind, I offer that this is the only LN2 failure I have found noted since production dates after March 2020.

With this said, once I will become responsible for financing my battery replacements they will be with a H5 or maybe H6 and the ASS system will neutered. This position is based on CoO and my assessment of the current quality/reliability of the technologies. I do reserve the right to change my position as additional data becomes available.

LN2 Failure Poll
 

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Discussion Starter #19
Interesting views from both. Some time ago, I found that the Japanese companies I had relationships with remained decuples of Deming and followed continuous process improvement methods. I yield to the possibility this may not be true in all cases, but would be surprised if it were not part of the Subaru culture. With this position in mind, I offer that this is the only LN2 failure I have found noted since production dates after March 2020.

With this said, once I will become responsible for financing my battery replacements they will be with a H5 or maybe H6 and the ASS system will neutered. This position is based on CoO and my assessment of the current quality/reliability of the technologies. I do reserve the right to change my position as additional data becomes available.

LN2 Failure Poll
You can neuter the ASS system with a battery replacement?
 
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