Have you always gone out to your car to start it upwardly, only to be met with flickering lights and a clicking sound? That most likely ways that your car's battery is dead. Only what if it happens every day? If so, and then you might demand a new bombardment or the machine could have a parasitic describe. Let's say the battery ends upwardly testing as good, how do you lot check the automobile for a parasitic depict?

What is a parasitic draw?

An Advance Auto Parts employee tests a car battery.
An Advanced Car Parts employee tests a auto battery. | Getty Images

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A parasitic draw is when the auto has a abiding drain on the battery even afterward the motorcar has been switched off. Some parasitic draws are slower than others, however, they are ever acquired by a short circuit or an electrical device that remains "on" after the ignition is close off, according to Beam Addict.

Some of the main causes of a parasitic draw include:

  • Aftermarket radio equipment
  • An aftermarket alarm system
  • A dome light
  • Faulty battery
  • Alternator diode

How do yous test for a parasitic draw?

If you suspect that your car has a parasitic draw then y'all can comport a test using a multimeter and a few other simple tools. The test itself can take a few hours, so be sure you lot practice this check when your schedule is cleared. Here are the tools that you lot'll need:

  • A multimeter – Must have an Amp (DC) reading of at to the lowest degree 10 amps
  • 8mm and 10mm sockets and wrench to remove the battery terminals
  • Needle-nose pliers or fuse puller
  • Zip ties or small clamps

The parasitic describe test itself is simple and straightforward, but fourth dimension-consuming. Having a friend to assistance could exist useful, but it's not actually necessary.

Diagnosing the battery drain

Car battery charging process using a smart charger
Car battery charging process using a smart charger. | (Photo by Michal Fludra/NurPhoto via Getty Images)

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When conducting a parasitic draw test, you'll need to check all of the fuse boxes in your car. Keep in listen that every car is unlike, so you might have ii fuse boxes in the engine compartment and 1 on the driver's side interior panel. However, some cars take multiple fuse boxes in the interior panels. Be sure to cheque your specific car'southward wiring diagram first.

  • Step 1: Remove the negative battery cablevision. You can do the exam on the positive cable, but it's much easier and safer using the negative side.
  • Footstep ii: Turn on the multimeter and brand sure it's set for DC, not Air-conditioning. Choose 10A or 20A and make sure the leads are in the correct locations. Then put 1 of the multimeter's leads on the negative bombardment post and the other on the disconnected battery last. Employ the cipher ties or clamps to go on the leads secure.
  • Step 3: Starting time removing and replacing fuses while checking the multimeter for a drop in Amps. Move to the interior fuse panel and bank check those equally well.
  • Step 4: When you finally pull a fuse that makes the Amps drop significantly, then you have institute the culprit. However, keep in mind that this test will betoken you in the right direction (like the alternator, for example), but you'll still need to set the main issue.
  • Step 5: Replace the negative bombardment cable

Some tips before yous get started

Before you offset the parasitic draw exam, remember to charge the battery completely first in order to become an accurate reading. Also, since you're testing the car for a draw when the car has been off for a while, brand sure to unplug whatever accessories y'all have in the automobile with the ignition off and let it sit for at least an 60 minutes. By doing and so, you'll effectively recreate the scenario where the car has been sitting with a depict on the battery.