The first thing to consider is the size of the battery. All car batteries belong to a particular group in size. This indicator determines whether the battery is suitable for a car according to its physical dimensions. This is the main indicator that you need to check before buying a battery. If the battery you buy is larger than a stock one, most likely, it won't fit in your car, no matter how good it is. The Subaru battery size usually has an indicator of 25 units. You can find out the exact sizes of this group of blocks on the Internet and compare them with your own battery. Subaru also uses reliable AGM systems, which have several advantages. Firstly, they do not have a liquid medium, so the electrolyte can't leak out. They use special glass fiber walls that absorb the fluid and contribute to a denser installation of lead plates. In addition, their case is very strong and monolithic. It is not afraid of vibrations and other mechanical influences. Secondly, the discharge of the battery is much lower than that of alternative batteries. Thirdly, they charge up to 100 percent much faster. Usually, it takes less than 2 hours. Fourthly, AGM batteries can work and start the car at low temperatures up to -35 degrees. These advantages make AGM systems very promising. Many Subaru cars, including the Subaru Outback, are equipped with such batteries. These batteries significantly exceed stock blocks in capacity, reliability of the case, and CCA.