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Subaru Low Battery Light

Common Reasons Behind Subaru’s Rapid Battery Drain

by Mechanics Direct February 24, 2023

One of the most common problems we see Subaru drivers face is a rapid battery drain, which can leave them stranded and frustrated. A car battery is a rechargeable battery that is used to power a vehicle’s electrical system. It works by converting chemical energy into electrical energy. When the battery is charged, a chemical reaction takes place between the electrodes and the electrolyte solution, producing lead sulfate and water. This reaction releases electrons, which flow through a circuit to power the car’s electrical system. When the battery is being used to power the car’s electrical system, the chemical reaction reverses.

Over time, the chemical reaction inside the battery will cause the lead plates to become coated with lead sulfate, reducing the battery’s ability to hold a charge. This is why car batteries eventually need to be replaced or recharged, but sometimes they die out before it’s time due to other reasons discussed below.

Old or Faulty Battery

One obvious reason for rapid battery drain in Subaru is an old or faulty battery. Batteries have a limited lifespan, and over time they lose their ability to hold a charge. If your battery is more than three years old, it may be time to replace it. A faulty battery can also cause a rapid battery drain, so if you notice that your battery is not holding a charge as well as it used to, it may be time for a replacement.

Parasitic Draw

A parasitic draw is when there is a constant battery drain, even when you’re not using the vehicle. If you suspect that your Subaru is experiencing a parasitic draw, you should have it checked by a qualified mechanic to identify the root cause of the issue.

Corrosion on Battery Terminals

Corrosion on the battery terminals can also cause a rapid battery drain. Over time, the battery terminals can become corroded, preventing the battery from properly charging. If you notice that your battery terminals are corroded, you can clean them with a wire brush. It’s also a good idea to check the battery cables for any signs of corrosion or damage.

Faulty Alternator

Electrical issues, such as a malfunctioning alternator, can also cause a rapid battery drain in your Subaru. If your alternator is not charging the battery properly, it may not be able to keep up with the demands of your vehicle’s electrical system. A faulty starter can also cause a rapid battery drain by drawing power from the battery even when the engine is not running.

Leaving Accessories On

Leaving accessories on, such as headlights, radio, or air conditioning, can also cause a rapid battery drain. Turning off all accessories when you’re not using them is important, as they can drain the battery even when the engine is not running. If you’re not sure if you left an accessory on, check your dashboard to see if any lights are on.

Extreme Temperatures

Extreme temperatures, both hot and cold, can also affect the performance of your Subaru’s battery. In cold weather, the battery may struggle to start the engine, while in hot weather, the battery may discharge more quickly. If you live in an area with extreme temperatures, have your battery checked regularly to ensure it’s working properly.

Faulty Voltage Regulator

The voltage regulator is responsible for regulating the amount of voltage supplied to the battery. If the voltage regulator is faulty, it can cause the battery to become overcharged, leading to a rapid battery drain. Signs of a faulty voltage regulator include dimming or flickering headlights and the battery warning light on the dashboard.

Short Trips and Infrequent Driving

If you mostly take short trips or don’t drive your Subaru often, the battery may not have enough time to fully recharge. This can cause a rapid battery drain over time. If you’re not driving your car regularly, it’s a good idea to use a battery maintainer or trickle charger to keep the battery charged.

High-Drain Electrical Components

Some Subaru models come equipped with high-drain electrical components, such as a powerful sound system or advanced safety features. These components can drain the battery quickly, especially if they’re used frequently.

Subaru Battery Repair

Book an Appointment at Mechanics Direct for Your Subaru Repairs

If you’re experiencing rapid battery drain in your Subaru, Mechanics Direct is here to help. Our expert technicians have years of experience diagnosing and repairing issues with Subaru batteries, and we serve drivers from North Chelmsford, Chelmsford, Dracut, Tyngsborough, Westford, and Lowell, MA. Contact us today to book an appointment and let our team of professionals get you safely back on the road.