Owners of the Subaru Outback often complain that the OEM battery is a little weak, with a low 490 cold cranking amp rating. Many owners have decided to upgrade when they need to replace their batteries.
Our brief review gives you the best options available to replace your Subaru Outback battery.
AT A GLANCE: OUR TOP 5 PICKS FOR SUBARU OUTBACK
| Image | Product | Features | Price |
|---|---|---|---|
 | Optima RedTop Group 25 |
| Check Price |
 | Optima YellowTop Group 25 |
| Check Price |
 | Northstar Group 24 |
| Check Price |
 | Odyssey Group 34 |
| Check Price |
 | Optima YellowTop Group 34 |
| Check Price |
3 Features To Look For When Buying Subaru Outback Battery
1. Battery group size: Dimensions + Terminal positions
One of the essential features to look out for when buying a Subaru Outback battery is the size. Manufacturers list batteries by group numbers, and the Outback battery is Group 25 as standard. The group number defines the standard battery size and the position of the terminals.
Before buying your battery, check the owner’s manual, as this should specify the correct battery group for your model of Outback. If you don’t have the manual, then measure the battery box. The standard dimensions for a group 25 battery are 9.1 x 6.9 x 8.9 inches.
However, as we mentioned, many Outback owners have decided to upgrade the larger battery size for more cranking power instead of getting a Group 25 one.
Subaru Outback Battery upgrade
Larger Group sizes vs. Group size 25 comparison table:
Group 25 | Group 24 |  Group 34 |
|
|---|---|---|---|
| Customer Rating |  |  | |
| Dimensions (in) | 9.1x6.9x8.9 | 10.3x6.8x8.9 | 10.3x6.8x7.9 |
| Dimensions (mm) | 230x175x225 | 260x173x225 | 260x173x200 |
| Terminal Position | Left Positive | Left Positive | Left Positive |
| Price Range | $224 - $325 | $133 - $674 | $220 - $375 |
Differences in dimensions between:
Group 25 vs. 24: The main difference in size between the group 24 and group 25 batteries is the length. This is the dimension when looking at the front of the battery, where the labels are attached.
The standard length of a group 25 battery is 9.1 inches, whereas the group 24 version is slightly longer at 10.3 inches. The other two dimensions are identical except for 0.1 inches difference in width.
Group 25 vs. 34: The group 34 battery is the most different in size compared to the group 25 equivalent. Not only is the length greater, at 10.3 inches, but the height is also shorter by an inch. Although spacers are available to compensate for the height difference, they are not usually required, and the standard battery clamp will work just fine.
Pros & cons of buying a larger battery
Pros
- More power
- Higher CCA
- Improved RC
Cons
- Possible need to modify your battery box
- Heavier than the OEM battery
- May be more expensive
2. Cold cranking amp
The main reason for fitting a larger battery is to gain more power, and the cold-cranking amps value (CCA) is particularly important. The CCA indicates how well the battery will crank your engine in cold environments.
The group 25 battery generally has a lower CCA than both groups 24 and 34. If you live in a cold environment, it may be worth considering an upgrade to a larger battery for this reason.
The standard Subaru battery only provided 490 CCA, whereas the lowest on the review batteries here is 620 CCA.
Here are 620 CCA, 720 CCA batteries:
Odyssey Group 34 850 CCA
Optima Group 25 720 CCA
3. Price
As with most products, a varied range of costs can be found. However, despite the higher power on offer from group 24 and 34 batteries, they can be found at lower prices than group 25 batteries.
The adage, “you get what you pay for”, is very relevant. A better quality, more expensive group 25 battery will often be better than a cheaper group 25 or 34 battery that claims to have more power.
See some cheap batteries for sale:
Optima Batteries D34 Battery
Optima Battery 25 RedTop
5 Best battery for Subaru Outback
1. Best Group 25 Battery for CCAs: Optima RedTop 720 CCA
Price range: $225-$235
Optima’s Red Top batteries are well-known and popular choices for automotive use, and the 8025-160 25 is no exception. This group 25 battery will fit perfectly in your Subaru Outback battery box without any adjustment.
Offering an impressive 720 CCAs, the Optima is far more powerful than the 490 CCAs of the OEM battery. Add the 90 minutes of reserve capacity to this, and it’s an excellent choice for a standard fit group 25 battery.
Optima claims it is 15 times more vibration resistant than standard batteries, helping to double the working life of the Optima.
With an excellent boost in power compared to the OEM version, there is little to say against the Red Top. However, if you have a power-hungry ICE system in your car, you may want to look for something with more than a 90-minute reserve capacity.
2. Best battery for reserve power: Optima 8042-218 Yellow Top
Price range: $280-$290
The Optima 8042-218 Yellow Top offers a slightly different specification to the Red Top version. As a standard group 25 size, it will fit your Outback with no modifications required but gives alternative power choices.
The CCA rating has been reduced to 620 amps, but this is still a significant boost compared to the OEM version. The yellow top shines with a reserve capacity of 100 minutes and an increased 48 amp-hour capacity—both improvements over the Optima red top version. You also get the Optima anti-vibration guarantee, helping to prolong the battery’s life.
However, the downside is the price of around $285, which is $60 more than the red top version. If you value the increased reserve capacity, then buy the yellow top, and if cold starting is more important, buy the red top.
3. Best value for money: Optima Group 34 Yellow Top
At 10 inches in length, the Optima group 34 yellow top battery is only 0.7 of an inch longer than the OEM fitment to the Subaru Outback. This means it should fit the standard battery box, but measure carefully before committing if you don’t want to make modifications.
Giving 750 cold-cranking amps (CCA) and 120 minutes of reserve capacity (RC), the Optima is a fantastic value at around $244. Optima also guarantee their design to be 15 times more vibration resistant than standard flat-plate batteries.
The Optima yellow top is hard to beat for a significant improvement over the OEM battery in terms of CCA and RC. Just make sure that your battery box is large enough and enjoy the increased performance.
4. Best group 34 battery for power: Odyssey 34/78-PC1500DT
At 10.85 inches long, the Odyssey 34/78-PC1500DT is an inch longer than the OEM battery, so the battery box may require modification. Height-wise, it is almost the same as a group 25 battery, so the standard battery strap should work just fine.
You’ll get a massive 850 cold-cranking amps from the Odyssey, giving you an easy engine starting in just about any environmental conditions. The Odyssey also has good staying power, with a reserve capacity of 135 minutes.
Internally, the battery’s design offers more power and better vibration resistance than spiral-wound designs employed by Optima and other manufacturers.
At around $304, the Odyssey gives similar power to the NorthStar, which is more than double the price. The NorthStar only beats the Odyssey in ultimate peak amps, so this may be something to consider, but we’re not convinced it is worth paying twice as much.
5. Best Group 24 choice for ultimate power: NorthStar NSB-AGM24
If you are looking for the ultimate in power, the NorthStar NSB-AGM24 is an excellent choice. As a group 24 size battery, it is an inch longer and taller than the standard fit, so you may need to modify the battery box or securing strap.
With a massive 840 CCA rating, you should never have an issue starting your Outback, even in the coldest environments. In addition, the NorthStar gives you a whopping 1500 peak amps for engine starting and a reserve capacity of 160 minutes.
Of course, there is a downside, and in the case of NorthStar, it’s the price. At around $674, it is the most expensive battery here by far, but if ultimate power is your requirement, it could be a price worth paying.
Tips For Buying & Replacing New Battery
Battery manufacture date: The date a battery was manufactured is stamped on the side. While sitting on the shelf, a battery can become discharged entirely in around six months, possibly causing internal damage. Avoid buying batteries getting close to being six months old.
AGM batteries are preferred: Compared to conventional wet cell batteries, the newer AGM technology offered in the batteries we’ve reviewed here gives improved power and reliability characteristics.
Connect a temporary power source while changing your battery: To avoid losing stored information such as radio presets, automatic gear shifting characteristics, and other data, you can attach a temporary power 12v power supply while changing your battery.
Conclusion
The standard Subaru Outback battery is known to be a little weak, but it’s easily rectified. There are several options available, including fitting a larger group battery. Just check it will fit if you don’t want to make modifications to your battery box.
