What is the most common cause of an excessive parasitic drain?

The most common causes of parasitic drain are under hood lights, trunk lights, headlights or glove box lights that do not turn off when the door is closed. Relay switches that are stuck in the “on” position can also cause a battery to drain.

Can a parasitic draw kill a battery?

If a battery goes long periods without being recharged by the alternator, those tiny milliamps drawn by parasitic devices will kill it. Even normal parasitic drain, also known as “key-off drain,” puts wear and tear on a battery. Allowing a battery to go dead for long periods of time will cause sulfation.

How do you diagnose a parasitic drain?

Pull the negative off the battery. Put the test light between the post and the ground wire. If the light illuminates, you have a draw. Use the fuse pull method to find the draw; when the light goes out, you found the draw.

What is acceptable parasitic draw?

A normal amount of parasitic draw for newer cars is between 50-milliamp to 85-milliamp current draw. A normal amount of parasitic draw for older cars is a reading less than 50-milliamp. Anything past these amounts indicates an electrical issue and should be addressed by a mechanic.

Which is an example of a parasitic draw?

Parasitic draw, also called drain, is the electric current that flows through a vehicle, both while it runs and after the ignition is turned off. You know how you can forget to turn off your headlights, and then your car won’t start the next day? Well, this is just one example of parasitic drain.

How can I find out if my car has a parasitic draw?

Luckily, you can usually find the cause of a parasitic draw yourself. Start by connecting a digital multimeter to the negative battery terminal of your vehicle. Then, remove the fuses one at a time while watching for changes in the multimeter’s reading. Once the reading drops, you’ve found the culprit and can take steps to repair it.

How to find the cause of parasitic battery drain?

When to look for a parasitic power draw?

Your battery could be near the end of its service life and it should be recycled and replaced with a new one. If the battery test shows that it is still good, then it’s time to start looking at a parasitic power draw. While you’re under the hood (or at Advance Auto Parts), test the alternator.

How to fix a parasitic drain on a multimeter?

Disconnect the negative battery cable. On the amperage side of the multimeter dial, set it to 20 amps. Disconnect the negative battery cable. Touch a lead to the negative battery cable terminal. Touch the other lead to the negative battery post, completing the circuit within the multimeter, which will display the amp draw.