Do Subaru Vehicles Need Frequent Battery Replacements?

Do Subaru Vehicles Need Frequent Battery Replacements?

Random and Sudden Premature Dead Subaru Battery

Are you experiencing a random and sudden premature dead battery in your 2015-2020 Subaru? Forced to carry a lithium charger just in case a sudden dead battery leaves you stranded? Well you’re not alone. Earlier this year, we began to receive complaints of Subaru batteries that would suddenly lose their charge, even when the car was being used everyday. Some owners report that they did receive replacement OEM batteries from their local Subaru dealers, but only to find themselves once again with a dead battery.

This has led to a class action lawsuit being filed for this battery issue. Subaru models reported plagued with this problem includes model years 2015-2020 Outback, Forester, Legacy, WRX and model years 2019-2020 Ascent. Is this just a result of a bad batch of Subaru batteries, or something much more serious? Let’s dig in.

Class action settlement has been announced: Subaru Battery Drain Settlement Announced. Insufficient Battery Capacity Failed To Support Vehicle Components

What Causes Car Batteries to Fail?

To start, it’s important to understand that no matter if a car battery is new or old, long periods of inactivity or short drives with accessories such as the radio and air conditioning running will cause a car battery to discharge.  This is because the alternator does not have ample time to fully recharge the battery. This can result in a weak and even dead battery over time. Other more common reasons for a car battery to loose charge are:

  • leaving an interior light on
  • leaving the headlights on
  • not completely closing the trunk
  • extreme temperature changes
  • defective alternator

Older batteries will start to show signs of going bad by a white/blue corrosion typically found on the positive terminal connector to your battery. Corrosion such as this will cause charging and low voltage issues.

Other charging or low voltage issue is when your battery is giving off acidic fumes or leaking battery acid. When this happens, you will see a clear film across the top of the battery case.

Both of these conditions create resistance between the battery and the cables, which causes low voltage issues and lost of power.

However, in the case of the 2015-2020 Outback, Forester, Legacy, and WRX models, owners are reporting that even when these cars are daily driven, accessories are off, their batteries loose charge and cause a no start situation requiring a jump start.

Understanding the Battery Warning Light

Most Subarus now have a battery warning light that will come on and then go right out when you start your Subaru. However if it comes on while you’re driving, then that’s an indication that your charging system has an issue, and most likely a failing alternator. It’s the alternators job to keep your Subaru running, but also to generate the power to recharge your battery. Your car battery’s main job is to start the car.

Subaru Battery Litigation

According to the current litigation, it sounds like the problem could be two-fold. First, it is alleged that the electrical system in these vehicles are subject to a continuous parasitic drain, even when the engine is not running. Apparently, these vehicles have a Controller Area Network (CAN) system which is designed to let components like electronic units, microcontrollers, devices, sensors and actuators communicate and work together without a host computer. The case goes on to state that the vehicles contain a manufacturing defect (including software errors) that results in the CAN system not entering the necessary sleep mode when the vehicle is turned off. As a result, the CAN system draws significant “dark current” (parasitic battery draw) even when the vehicle is turned off and not being operated, thereby draining the battery.

CAN system not entering the necessary sleep mode when the vehicle is turned off

Second, in addition to the “dark current,” the complaint states that the batteries in the vehicles are not designed to be continually drained down to low volumes of power. When this occurs, the battery’s total charge, its lifespan is shortened, until the battery loses all power. The alleged defect therefore makes it necessary to replace the battery in vehicles far more often than is typical with other, non-defective vehicles.

Batteries in the vehicles are not designed to be continually drained down to low volumes of power

The case is currently pending in New Jersey federal court and is captioned In re Subaru Battery Drain Products Liability Litigation.

We will continue to monitor the case and provide updates to this page as they become available.

April 25, 2021 Update
Case is currently being litigated in NJ on behalf of Subaru owners. Please keep all receipts related to battery drain repairs and replacement batteries.

Last Updated on September 30, 2022

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