Why Does My Car’s Battery Keep Dying?


If you’ve recently found your car with a dead battery a time or two, you may find yourself wondering “Why Does My Car’s Battery Keep Dying?”

Some of the most common reasons for a car battery to die more than once include a failing battery, loose or corroded battery connections, parasitic electrical drains, and charging system problems.

In some cases (like if you’ve recently upgraded the stereo or added a bunch of other electronics), you may have exceeded your alternator’s ability to charge the battery, at which point an alternator upgrade is recommended.

Why Does My Car’s Battery Keep Dying? – Bad Battery

Usually, a battery will die slowly and provide warning signs in advance. There are exceptions, of course, such as when an internal failure occurs as a result of a bad cell. When that happens, you’re likely not to have any warning signs and will find your car or truck in need of a jump every time you start it up.

Luckily, free car battery testing can be found at just about any local parts store!

Loose, Corroded, or Worn Battery Connections

Loose or corroded battery terminals can impair your battery’s ability to transmit power, preventing your vehicle from starting. You may also experience slow cranking or notice a rapid clicking sound when attempting to start the engine.

Bad battery cables can create some of the same symptoms. So, you may want to test your battery cables and find out if they’re the cause of your problems.

Why Does My Car’s Battery Keep Dying? – Charging System Problems

The charging system in your vehicle is critical to its operation. However, everything in the charging system needs to continue performing it’s job, or the system as a whole fails.

If the alternator does not work at full output, the additional power for the lights and the ignition system of the car will come from the battery, not the alternator. This situation can result in a battery that is undercharged or completely dead.

In modern cars, however, the alternator is typically computer controlled and has a variable output, so diagnosing an alternator problem can turn into a bit of a headache.

Parasitic Electrical Drains

Parasitic Electrical Drains are things that continue to drain power from the battery after your car or truck’s engine is off. Digital multimeters are handy little tools for diagnosing battery drains.

Make sure your vehicle is turned off, and remove the key from the ignition.

Switch the multimeter to DC Amps and set it to the highest amp level. This will avoid damaging the device.

Next, remove the negative battery cable from your battery terminal. It should be black. Be careful not to allow the wire to touch anything grounded.

Then, connect the multimeter probes to the battery cable. Be careful to do this level with the battery terminal, but keep the multimeter off to the side.

Now you can check the reading on your multimeter to see what the parasitic drain is. If no reading shows, slowly reduce the setting until a reading appears.

A normal reading for a newer car falls between about 50 to 85 mA. For older cars, an ideal reading is below 50 mA. If your reading is higher than these numbers, you have an electrical problem on your hands.

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