How to check for battery drain with multimeter

How To Check For Battery Drain With Multimeter?

Having a reliable and running vehicle is always very important to every household. You have kids to take to school, errands to run, things to pick up, and most importantly to get to your job.

Most car owners, though, know nothing about how their vehicle runs. That’s why I often review many DIY tasks that you can do at home to save yourself money and headache in the future.

Let’s take a look today at ways for you to check if there is battery drain happening on your car.

What is battery drain?

When your car is not running, typically the battery should have nothing pulling electricity except for extremely minimal electricity that controls minor items in your car for security.

What can happen, however, is different wires and metals can start moving around inside your car which causes unwanted electricity to start flowing through your vehicle.

This is battery drain and if you’ve found yourself with a dead battery more than once but you didn’t leave your dome light or other lights on accidentally, then it’s important to check if you have battery drain happening as well.

How to check for battery drain?

What you’ll need:

  • Digital Multimeter with a 20amp fuse
  • Gloves and Eye Protection

Before you start:

Make sure your battery is fully charged before you start. To do this, startup your car and let it run for at least 10 minutes.

Unplug any unnecessary accessories like a GPS, phone charger, any other cigarette lighter item, amplifier for speaker system/subwoofer, etc.

!!! Always wear safety equipment when working with any electrical items in your car so you avoid any shocks !!!

Check for battery drain:

  1. Start by removing the negative side battery cable from your car battery (this is the black one).
  2. Connect the black wire from your multimeter to the port listed as “COM.”
  3. Connect the red wire to the “10A/20A” input port on your multimeter. Make sure you do not put the red cord into the “mA” input port on the multimeter as it will not work for this test and can often damage the multimeter.
  4. Set your multimeter to measure Amps (each multimeter can be different so you’ll have to check your instructional manual to determine which setting to use).
  5. With the black cord from your multimeter, place the metallic prong on the negative(black) battery output.
  6. Wait for the results of the test on your multimeter’s screen. If your multimeter is reading more than 30-50 milliamps, then something is definitely wrong and too much electricity is being pulled from your battery.

How to confirm what is draining your battery?

car battery

If you want to check what is draining your battery, you can do this with some very easy steps.

  1. Go to the fuse panel located usually under the steering wheel of your car. Each car may be different though.
  2. Start by pulling out one fuse (best to start in a certain order and not to just do it randomly).
  3. Complete the steps above. If your battery still has battery drain, then it was not due to items on that fuse.
  4. Replace the fuse and pull another out. Continue doing these steps until you encounter a specific fuse which brings the amps down to an acceptable level.
  5. Depending on which fuse was causing it, you will now know the general area that is causing the issue.

If you’re not very familiar with your vehicle, the next steps can get quite complicated and depend on what type of car you have and what devices are affecting that circuit. You’ll need to next check every device that’s connected to that fuse and disconnect each electrical device one at a time to determine which is causing it.

Once you’ve identified the cause of the drain exactly, you’ll need to check the wiring and remove it and re-attach it. The goal here is to get everything to have a tight connection again so it no longer pulls unwanted electricity from your battery.

!!! If you are unsure of any steps along the way, it’s best not to play around with it and take it to an expert !!!

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