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Had my wife's Legacy serviced and the tech wrote on the report that her 6 month old battery needed to be charged. My mulitmeter showed voltage at 12.1. She drives mainly short trips and since that is what I had been doing with my 2019 Touring, I checked my battery. It was 12.15. Surprised that the alternators can't keep battery fully charged. Checked it again after a 30 mile trip on the interstate and battery was at 12.45. Could this be the reason for the early battery failures...chronically undercharging?
 

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2021 Ascent Touring Brilliant Bronze
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A fully charged battery is around 12.6-12.8 at rest. Brand new batteries can float around 12.8 to 13.1. If memory serves 12.3 is at around 50%. 12.1 is pretty much dead.

The GM's I had would usually end up at around 12.6. I think the electronics were programmed to charge to that point as when I would put the charger on it, the battery would creep up to 12.8.

Considering my kids are remote learning, it is not as big as a deal; however, during day's off, week breaks, I would throw the charger on the vehicle for a day or two. Worse case, over night. The short 10 minutes here and there trips and then sitting waiting for kids with the vehicle off, but other stuff running, does not really give the engine a chance to give a good charge. At least once a quarter I like to put the cars on the charger. This is regardless of the make or model of the vehicle.

With winter approaching I would recommend throwing the battery on a charger. It is very hard to freeze a charged battery. It has to get like -80F (I can't remember the exact number). A dead battery will freeze at 32F/0C though.

All I have is a 2 amp trickle charger. It is temperature compensating, desulfating, and few other features. Having a higher amp charger does come in handy if the battery is dead as it will charge it faster. For the "maintenance" charging I do, my little 2 amp is fine.
 

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^ I'm now sitting in the parking lot quite a bit, to wait for my daughter to finish up with her sport practice.

With only the head-unit running (sometimes charging my phone), I re-start the car when the hourly "Battery Saver" function trips. I've yet to see any issues, but conditions have so far been mild.

It'll be interesting to see what happens once it starts to get colder (we're going to pass the 40-deg. F. mark this coming week).

In addition to my trusty jumper cable, I also carry a jump pack that I routinely maintain. Hopefully I won't have to call the wifey to come rescue me any time soon. ;)
 

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2019 Subaru Ascent Touring (Canadian Edition) -- Ice Silver Metallic
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Yep, frequent short trips and driving it stuck in slow moving traffic jams will shorten the life of the battery as it will start to sulfate if never fully charged.

I usually top up the battery every couple of months.

When the OEM battery goes, I'll use an AGM battery instead. They are work better in these high drain conditions and will last longer as it readily accepts a charge better than the old flooded type batteries.
 
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