Have you ever gone out to your motorcar to commencement information technology up, only to be met with flickering lights and a clicking audio? That most probable means that your car'south bombardment is dead. But what if it happens every day? If then, and so yous might need a new battery or the car could have a parasitic draw. Let's say the bombardment ends up testing as good, how do you check the car for a parasitic describe?

What is a parasitic draw?

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

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A parasitic draw is when the motorcar has a constant drain on the battery even after the car has been switched off. Some parasitic draws are slower than others, however, they are always caused past a short excursion or an electrical device that remains "on" after the ignition is shut off, according to Beam Addict.

Some of the primary causes of a parasitic draw include:

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

How exercise you test for a parasitic draw?

If y'all suspect that your automobile has a parasitic depict and then you can conduct a test using a multimeter and a few other elementary tools. The test itself can take a few hours, so be sure yous do this bank check when your schedule is cleared. Hither are the tools that yous'll need:

  • A multimeter – Must have an Amp (DC) reading of at least x 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 draw exam itself is unproblematic and straightforward, but time-consuming. Having a friend to assistance could be useful, simply it'due south not really necessary.

Diagnosing the battery drain

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

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When conducting a parasitic draw test, you lot'll need to check all of the fuse boxes in your auto. Keep in heed that every car is different, then you lot might have 2 fuse boxes in the engine compartment and one on the commuter'south side interior panel. However, some cars have multiple fuse boxes in the interior panels. Be certain to check your specific auto's wiring diagram first.

  • Pace i: Remove the negative battery cable. Y'all can practice the test on the positive cable, just information technology'south much easier and safer using the negative side.
  • Pace 2: Plough on the multimeter and make sure information technology'south set for DC, not Air conditioning. Choose 10A or 20A and make sure the leads are in the right locations. Then put 1 of the multimeter'southward leads on the negative battery post and the other on the disconnected battery concluding. Use the goose egg ties or clamps to keep the leads secure.
  • Step 3: Start removing and replacing fuses while checking the multimeter for a drop in Amps. Move to the interior fuse panel and bank check those as well.
  • Step 4: When you finally pull a fuse that makes the Amps drop significantly, then you lot have found the culprit. However, keep in mind that this examination will point you in the right direction (similar the alternator, for instance), but you'll still need to fix the main issue.
  • Due southtep 5: Supercede the negative bombardment cable

Some tips before you become started

Before you start the parasitic depict examination, recollect to charge the battery completely first in social club to become an authentic reading. Also, since you're testing the car for a draw when the car has been off for a while, make sure to unplug any accessories you have in the machine with the ignition off and permit it sit for at least an hour. Past doing so, you'll effectively recreate the scenario where the car has been sitting with a describe on the battery.