2012 Subaru Legacy batteries die every two years

I have a 2012 Subaru legacy 6 cylinder and every 2 years the battery will just go completly dead, no warning at all, jump starting is futile, battery replacement is mandatory

Where do you live? Climate plays a factor in battery life. Since it’s been this consistent, I think it would be worth taking your car into your mechanic to have the charging system checked (starter/alternator/battery) as well as checking for a parasitic draw from your electronics. Have you had anything aftermarket installed?

Well, I live in Hurst, Texas. Charging system checked out fine, within last 2 months we had stereo, with all bells and whistles,and a dash-cam, Blackvue model # dr750s2ch with cellinkb2 battery for parking mode and draw from car battery will stop after 11.6 volts charge left in car battery. car security system ,factory does flash on dash continuously while car is parked.

I had a similar problem with a VW, kept losing batteries. I was able to co-orelate it with the car sitting unused for 4-5 days. Tried turning off the dome light and that solved the problem. The light is programmed to stay on for a short period after you leave the car. Apparently it was sometimes staying on and draining the battery.

My point is that you have to analyze what occurred to cause the battery to die. It may be intermittent as mine was, so it may take some guesswork.

If it’s happened 2 years ago, it’s not the options you recently installed (at least that is how I interpret your last post).

“after 11.6 volts charge left in car battery” ? can you explain this? 11.6 means the battery is partially discharged.

Are you saying the battery shows 11.6 volts immediately after the car is shut off?

In retrospect, are you assuming that because the starter motor will not crank the engine that the cause is the battery? If so, that brings up a few points.
I mention this because you say jump starting is futile.

IF that is the case then maybe the range selector switch (a.k.a. neutral safety) is bad.

I’ve heard before, that generation of Outbacks had misleading trunk light, which was NOT automatically turned off and was draining battery unless turned off, and the location was such that some owners would oversee it.
I can totally imagine Legacy would share electrics design to Outback

A battery at 11.5 volts often won’t be able to crank the engine. Especially in cold weather. That’s a very discharged battery. Assuming the charging system has already been tested, and this car is driven daily for at least 5 miles most every day. If so, there’s probably something in the car that’s turning on when it shouldn’t be when the car is parked and not being used. A shop would install an amp meter in the main battery circuit to monitor the overall current draw when the car is parked. If there is no unexplained current draw, the problem is the battery. But usually there is big draw discovered, and then it is just the normal electrical sleuthing to determine which circuit it is, then which device. Often this is caused by

  • a dome light turning on b/c of a faulty door switch,
  • a hidden light in the glove compartment, trunk, under the hood, etc.
  • alarm system, or stereo, especially if they are not original to the car.

Is a two year service life for a battery unusual in the Dallas/Fort Worth area? It isn’t in the southwest for some drivers, those that drive around in the afternoon heat, the engine heat cooks the battery.

I replace a lot of batteries under warranty that are less than two years old however my batteries last five years or more. If I have to drive in the afternoon heat of 100F plus, I open the hood when I get home to let the heat escape.

What I was getting at was the possibility of a faulty neutral safety switch that is erratic. That would cause a stone dead no-start condition where jumper cables would do no good.

I live in OK where it’s plenty hot in the summer and do not suffer repeated battery failures. The one in my LIncoln is 4 years old, the one in the Camaro is 6, and the Sonoma has a 7 year old battery which tests fine but is going to get replaced anyway rather than risk it.

A hot climate is one factor, driving for an hour in city traffic with an average speed of 15 to 20 MPH makes the engine compartment much hotter than rural driving and will greatly shorten battery life.

The dash cam is new (1month old ) The battery has been replaced every 2 years since 2012, like clockwork. No warning just go to start car and battery is dead and trying to jump doesn’t help.