I disagree that this is "everything" you need to know...

AGM batteries are more tolerant of abuse, such as being discharged or high/low temps or the demands of AS/S, and they take up charge faster, which is an issue with the eco charging of modern cars. I suggest you review some of the battery threads here.

They also last longer so, over time, the extra cost is warranted, if you expect to keep your car longer than the warranty period.

 

Here's another. The OEM battery life can likely be extended through maintenance. Check the water/acid level and add distilled water if low.

 

1. Technically a battery life span is 2-5 years.
2. If your battery dies earlier than expected, I would blame the extra load put on it by the start/stop system.
3. Yes you can put an aftermarket battery in.
4. No you don’t need an expensive AGM battery.
5. The start/stop can be bypassed with the “auto start stop eliminator”. I have one and I love it.

FYI - the battery in the cars with stop/star is different. That is to compensate for additional starting. BTW - I have the stop/start eliminator. My theory is the battery should last longer. We shall see.

 

Battery Guru,

What is the largest size battery that will fit in the battery bay?

 

24F Vs 35 Car Battery: What's The Difference? - Car, Truck And Vehicle How To Guides - Vehicle Freak
There are 6 cells in both batteries.

 

I would disagree with a few of those points. One of the cheapest upgrades towards reliability one can do to their Subaru is an AGM battery. The factory batteries are garbage. I also run AGM batteries in our BMW and Porsche with great results.

 

Couldn't agree more! There are so many posts here about "upgrades" like mudflaps. A decent battery to replace the crappy OEM should be at the top of the list. Especially if you intend to go off road and up into the mountains in the winter.

 

My original OEM battery is now a bit over 3-1/2 years old. Most of my drives are very short (under 5 miles round-trip). I expect it to last a minimum of 5 years. Maybe I've just had good luck with car and motorcycle batteries, but I've never had one go bad with less than about 7+ years of use. Only my motorcycle batteries live on chargers during the winter, never the Crosstrek's.

 

Our 2018 still has the OEM battery and I take care of my stuff as well. I can usually get 7-8 years out of a battery. Unless I let it discharge severely several times. In my experience THAT's what usually kills them early (<5 years). Also something I've learned, and of course it's purely anecdotal, but vehicle alternators, by & large, are NOT battery chargers. They are strictly battery maintainers. If a person lets their 12VDC battery get severely discharged, jump starts it and expects the alternator to recharge it... not only does it not charge effectively or efficiently, but it slowly damages the alternator 'lectronics. I've done a LOT of 'testing' on this, having been a tow truck driver/fleet vehicle manager for several years.

 

If that's the case, an AGM would be a better option as they tolerate heat better.

 

I haven't measured but it would be difficult to fit a much bigger battery in there. Again, better to install a better one than a bigger one.

 

	24F Group Size Battery	35 Group Size Battery
Dimensions	10.3 x 6.8 x 8.9 inches	9.1 x 6.9 x 8.9 inches
Size	Longer sized battery	Smaller sized battery
Weight	44.5 pounds	40 pounds
Cold Cranking Amps	Between 840 CCA and 1050 CCA	Between 550 CCA and 740 CCA
Reserve Capacity	Higher reverse capacity rating	Lower reverse capacity rating
Universal	You can replace 24F and 35 batteries	The battery tray will require alteration to replace a 35 with a 24F battery
Application	Used in the deep cycle stand-by or float applications	Used in cars, trucks, and SUVs

 

1050 CCA seems unlikely. If you can find one, the Odyssey Extreme is 850 CCA.

 

Cars today have a battery management system to make sure you dont charge your battery in the name of insignificant fuel mileage savings. Its part of the problem on new cars.

 

Cars today have a battery management system to make sure you don't charge your battery in the name of insignificant fuel mileage savings. Its part of the problem on new cars.

Yeah, manufacturers are doing whatever they can to meet CAFE standards. AGMs take up charge faster so I wonder how that works as the algorithm is probably assuming a regular lead acid battery.

 

I had the Odyssey Extreme in my 2013 Outback and it was the best battery I've ever purchased.

Yes, it cost more, but it's performance was much better in cold weather.

I didn't "go bigger" as many did in the Outback forum. I just kept stock size as I'm not running some crazy audio in it.

After the Outback got totaled, one of the techs at the dealer asked if he could take the battery, I told him go for it, just stick some used one in its place.

He now has it in his Subaru. Quite happy with it.

 

I had the Odyssey Extreme in my 2013 Outback and it was the best battery I've ever purchased.

Yes, it cost more, but it's performance was much better in cold weather.

I didn't "go bigger" as many did in the Outback forum. I just kept stock size as I'm not running some crazy audio in it.

After the Outback got totaled, one of the techs at the dealer asked if he could take the battery, I told him go for it, just stick some used one in its place.

He now has it in his Subaru. Quite happy with it.

Even though they cost more, they last longer so that's a mitigation, and definitely perform better.

 

https://tires.costco.ca/Batteries/Product?ItemNo=8214441&batteryname=Group-35-AGMAbsorbent-Glass-Mat-Automotive-Battery&BatteryType=Automotive&lang=en-ca

Group 35 Automotive Battery Battery | Costco Batteries

 

CONSUMER REPORTS

Best Car Batteries for the Money
Consumer Reports' tests highlight the batteries that balance performance and price

By Jeff S. Bartlett
Updated January 4, 2023





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Illustration: Kiersten Essenpreis
Car batteries are essential—and expensive. The average price in our latest car battery ratings is $160, with one model costing more than $300. Taking the time to research the best car battery for the money can truly pay off.

We recently posted our ratings of the best car batteries, highlighting the top-rated choice in each size we test. With this list, we’re looking at value—factoring performance and price—for our CR Best Buys. (See our complete car battery ratings.)

“The best value may be in choosing a strong performer that can be had for much less than the cost of the top battery,” says John Galeotafiore, who oversees testing of car batteries at Consumer Reports.

MORE ON CAR BATTERIES
CR's Car Battery Ratings & Buying Guide
Best Car Batteries of the Year
How a Car Battery Charger Can Keep Your Vehicle Ready to Go
How to Jump-Start a Car With a Dead Battery
How Hot Weather Affects Your Car Battery and What to Do About It
Identifying the CR Best Buys highlighted in our ratings starts with our test results. Each year, we purchase 150 individual batteries and put them through a grueling series of tests, measuring how they perform in extreme cold and heat and how long they will last if you leave your headlights on.

Our testers go to great lengths to evaluate the batteries. For example, battery life is measured by repeatedly discharging and recharging each battery about 3,000 times at a test temperature of about 167° F for 15 weeks or until performance drops to unacceptable levels. This simulates the hot under-hood conditions a battery can face during the summer, the toughest time of year for batteries because of the heat.

Absorbed glass mat (AGM) batteries tend to dominate our ratings. These pricey, maintenance-free batteries use a glass mat separator to move the electrolyte solution between the thin battery plates. AGMs are built to better stand up to repeated draining and recharging cycles than traditional lead-acid (aka “flooded”) batteries. AGMs are becoming standard equipment in more cars because modern features such as fuel-saving stop-start systems, electronic safety and convenience features, and power outlets for mobile electronics increase the demand for power. You should replace the battery in your car with the same size and type, but you can upgrade from a traditional battery to an AGM battery.

“If you live in an area with extreme temperatures and are looking for a maintenance-free battery, consider getting an AGM,” says John Banta, senior test project leader at Consumer Reports. “High heat can affect the life of AGM batteries, much like flooded batteries, but they tend to perform better overall in our tests.”

If you don’t need the capability to meet those demands, you can find traditional flooded batteries that are a better value. Our analysis has found that a traditional battery is the better buy in most categories we rate.

Below, we present Consumer Reports’ Best Buys—the best car batteries for the money—in these sizes: Group 24/24F, Group 35, Group 47 (H5), Group 48 (H6), Group 49 (H8), Group 51R, and Group 65. These group numbers indicate battery sizes, in the same way AA and AAA indicate the sizes of batteries you’d use to power home electronics.

Size 24/24F (top terminal): Fits many Acura, Honda, Infiniti, Lexus, Nissan, and Toyota vehicles.

Size 35 (top terminal): Fits most Japanese nameplates, including many recent Honda vehicles, most Subaru vehicles, and most Mazda, Nissan, and Toyota vehicles.

Size 47 (H5) (top terminal): Fits many Buick, Chevrolet, Fiat, and Volkswagen models.

Size 48 (H6) (top terminal): Fits many vehicles from Audi, BMW, Buick, Cadillac, Chevrolet, GMC, Jeep, Mercedes-Benz, Mini, Volkswagen, and Volvo.

Size 49 (H8) (top terminal): Fits many vehicles from Audi, BMW, Hyundai, and Mercedes-Benz.

Size 51R (top terminal): Fits many vehicles from Honda and Nissan.

Size 65 (top terminal): Fits large cars, trucks, and sport/utility vehicles from Ford or Mercury.

In our list of select car batteries, we show ratings for:

Overall Score
CCA, aka cold-cranking amps: How well the battery starts an engine during extreme cold weather.
Life: How the battery performs through repeated draining and recharging.
Reserve capacity: How long it can supply energy if the car’s charging system fails.

Group 24/24F
QUICK TAKE
90

Legend Premium 8424F
RECOMMENDED
NAPA Legend Premium 8424F
Price: $130
CCA
LIFE
RESERVE CAPACITY
See all Car batteries Ratings
Group 35
QUICK TAKE
85

35-640B
RECOMMENDED
Bosch 35-640B
Price: $125
CCA
LIFE
RESERVE CAPACITY