Have you seen the battery sticky up top,

Lot's of info in there.

What is the date stamp on that Everstart ? Was it a Max Everstart, or just the low cost one ?

I've been using Walmarts Max Everstarts for many decades now, they were one of the top-rated batteries years ago.

Here's my cheat sheet,

 

The threshold for a recall is generally something that affects the operation of a vehicle in a way that affects safety. While one could argue that needing a new battery every few years affects safety, it's not an imminent safety problem, and it's something that can be managed. Subaru does have a kind of service campaign type of thing to switch to a larger battery, the stuff that @Max Capacity shows on his sheet. It could be done under warranty or you can pay out of pocket.

EFB = Enhanced Flooded Battery, and it's designed to take the duty cycle of start/stop, and an AGM battery is also capable of handling it. A regular flooded lead acid battery cannot.

Was the Costco Interstate battery AGM or regular flooded?

Whether you have an EFB, regular flooded, or AGM battery, they are all essentially lead acid batteries and chronic undercharging will cause any lead acid battery to deteriorate in both capacity and ability to accept a charge. It's a slow downhill spiral. To determine if a battery is degraded you can't just check voltage - it needs to be checked for voltage sag under load - load testing. The reason why a battery that shows 12.6 volts might have trouble starting a car is that under the load of the starter, it may dip to 9 volts and not be enough to start the car.

So if you do mainly short trips, or infrequent driving, it's possible that your battery is chronically undercharged. When I have bought batteries from Costco or NAPA they have always needed hours of charging to really fill up. In the old days parts stores would charge a battery before selling it but now they just hand it to you. They aren't so undercharged that they won't work, but that doesn't mean they're fully fully charged when you get it. I recommend that no matter where you get your battery, you use an external charger to top it off when you get home so that it doesn't start deteriorating from day 1.

There is a workaround to force the car's charging system to better charge your battery for short trips or infrequent driving, and it may sound silly but it's to run the car with your parking or headlights lights on. Even then, there's no guarantee that a 5 minute trip will recharge the drain of starting the car plus the parasitic drain that it's been experiencing since the last start. It's still good to do periodic external charging. Many modern cars have "smart" alternators that are designed to pull back on charge voltage to save a little bit of fuel. When the alternator is trying to charge at higher voltage it puts mechanical load on the accessory belt and at idle the car will compensate by adding a little bit more fuel to keep the idle steady. So as a fuel saving measure, at idle the car may reduce alternator voltage.

The benefit of a larger battery is simply that you have more headroom before the battery's deterioration gets so bad that it won't start the car. It's not a cure.

 

Great explanation there. So the question is, do you only drive the car for short distances ?

I know it's not the same car, but, my 2018 just sat in the garage for 16 days, I checked it's MaxEverstart battery before starting it, voltage was 11.7, I put the battery in June 2022. The car started fine, like it always does. Most of our driving is 10 miles or more. We do make short trips, but not very often. Our cars will sit for days in the garage, at times. Both retired.

 

The only time I drive more than 5 miles is when I'm taking someone to the hospital for treatment, which is about once every 2 weeks.

11.7 volts is an undercharged battery, but that doesn't mean it can't start a car if it doesn't dip to say 9 volts under load, but it needs a recharge.

The state of charge of a battery doesn't reflect its underlying health, and the ideal voltage depends on temperature.

 

I'll add, I didn't start the 18 until I knew we were going to be driving it for distance when it had that 11.7V.
Funny story about that drive, we had an appointment 13 miles away, got about 10 miles towards there, when we remembered we forgot something, so turn around and drive back home, get the item, turn around drive back down there.

See not many short distance drives...LOL I've also posted, sometimes, we'll search google for restaurants near me, find one say 30-40 miles away and make a date night of it. Just to make sure the battery is charged...

 

Keep in mind that opening the door, as well as the hood will wake the car up causing a bit more draw from the battery. that 11.7v mght not represent the battery’s charge at rest.

That said, having the battery at less than 12.6 for extended lengths of time will result in the battery failing sooner than later. Lead acid batteries really need tobe fully charged all the time for a long life.

 

Is a regular battery is sufficient if I turn the stop/start feature off every trip?

 

Modern cars have more parasitic drain and Subaru uses an EFB for the Ascent which does not have start/stop, and shares the 2.4 turbo engine.

If you always turn off stop/start a regular flooded battery won't deteriorate as quickly as it would have if you continued to use stop start, but it probably won't last as long as an EFB or AGM, and typically a battery warranty isn't valid if you used the battery in a vehicle it wasn't designed for.

 

To answer your question, the dealership adviser that told you this is showing their ignorance.

You can use an EFB or AGM battery but not a normal lead acid battery.

I believe this is specified in the owners manual. If you do not have a copy you can download one from the Subaru US website.

Seagrass