All Wheel Drive Auto: Independent Seattle Subaru Service


Some thoughts on batteries and your Subaru

A funny thing happened to me this weekend, I had a dead battery on a 3 year old vehicle, our shop truck, the only non Subaru in the fleet. It wasn’t funny in the ha ha ha sense but just so ironic, as on a daily basis it seems we get to counsel a Subaru owner about the three year old battery in their Subaru no longer being up to the task of maintaining power overnight to all of the various modules and then starting the car up in the am, and then it happens to another make in the exact same way way it happens to so many of our customers. Of course I needed to use the truck to pick up the shops trailer and help out a customer, so just like it happens to so many of our customers the timing couldn’t have been worse, and there was zero warning signs. It was truly fine the day before, and simply will not hold a charge anymore.  Batteries have to be able to take a charge and maintain a charge, the latter being the most important part on newer vehicles. Modern vehicles have many more modules or computers that need constant power, so many more systems that need to be powered on at start up all at a time when manufacturers are all about cutting costs. So during a period when the battery needs to be the best, companies are looking to save, and it is difficult to see how those two things line up in our favor. The biggest factor in the shop truck not starting Sunday was the temperature dropped, increasing the amount of cold cranking amps that were going to be required to turn over a cold engine. Battery related issues will always show themselves when there is a spike either up or down in temperature.

What we see day in and day out at the shop is that since about 2015, Subaru vehicles will come with a battery that will last the warranty period, and typically not much longer than that.  It is not uncommon on a modern Subaru to have a dead battery if it sits at an airport for a week while you are on vacation, the older the battery the lower your expectations should be. 

It’s very important to understand that not all batteries are created equal.       

In the same way that the isles of a store have a lot of selection for quality and price for batteries for flashlights and other electronics the exact same is true for all of the names you might see for batteries for your car. Even batteries sold under the same name will have different countries of origin and the quality also varies.

If you have a smoke detector that requires scaffolding to change the battery, chances are you are not going to buy a cheap one, well at least I won’t, as I hate heights and really don’t want to do it again any time soon. I use this same logic when selecting what battery I would want to install, and more importantly offer to our customers.  

At the shop for your Subaru we use an Interstate battery and we use one with higher ratings than what your Subaru came with from the Factory, we do this because I want you to have less trouble not more.  

A note about all Subaru’s since 2005 for most and 2007 for all, if the battery goes dead and or is replaced without saving memory, the idle tables in the ECM (Engine Control Module) will need to be rebuilt, this is also known as a relearn. 2010 and newer Subarus may have to have the window pinch mode reset, 2015 and newer also the rear hatch reset.  Before starting a Suabru that has had a dead battery and or one replaced, turn the key to the on position and let the gauges sweep for at least 10 seconds, back to off, back on than start it. This ensures all modules receive power prior to starting and can help avoid annoyance later.

Thanks for reading 



6 Responses

  1. Justin –

    Fabulous site. Just experienced the same as you did on 10/28/19 with a dead battery on a low-mileage 3-year old vehicle. Mine is a 2016 Subaru Legacy Limited with a 2.5L FB25B non-turbo engine. Sat 9 days after drive; would not start. Is the leakage to accessories that much?
    Getting a Delco 25 PS from a small independent neighborhood garage. (He has no other choice.) Is an on/off switch at pos. terminal a suitable remedy? Other ideas?

    Thanks, Mike

    1. Hey Mike,

      If you purchase the Interstate “MT” series batteries, not the junk at Costco you wont have any problems. If you can truly only get the Ac Delco and its going to sit, I would suggest the battery maintainer.

      Hope that helps


  2. Thank you very much for your Battery comments. It is a very good input.
    I wander if I can ask you an unrelated question,
    I have a 2017 Subaru Forester and my A/C doesn’t feel that is cold enough.
    The Dealer checked in and out temperatures and tells me that by reading and comparison to other cars it is working as it should.
    Is there anything else that can be measured, like gas pressure?
    To compare with other cars my car is not as cold especially in a hot day.
    Thank you very much for all your support
    Benny Rubin

    1. Hello Benny,

      Thanks for the kind words.

      Yes, there are tests outside of saying it feels like every other 2017 Subaru Forester that can be done.

      A set of gauges can be connected to the AC system service ports and high and low side pressures can be measured up against nominal values at specific outside temperatures. Its the best way to understand if the system is filled to capacity, aside from removing the refrigerant and measuring the amount that came out vs specifications.

      Hope that helps.


  3. You are a Subaru wizard Justin and I sooo wish I lived closer to you! Thanks for all your posts from an admirer in Iowa…..

Leave a Reply

Your email address will not be published. Required fields are marked *