How to Check Battery Discharge with a Multimeter (5 Step Guide)
Content
People don't often check their car batteries for voltage spikes, but if done periodically, it can be a great preventative tool. This battery test is important to keep your vehicle running efficiently at all times.
This article will help you easily learn how to check battery discharge with a multimeter. I will help you determine the cause of your battery problem, as well as how to fix it.
Checking the battery discharge with a multimeter is very simple.
- 1. Disconnect the car battery negative cable.
- 2. Check and re-tighten the negative cable and battery terminal.
- 3. Remove and replace fuses.
- 4. Isolate and fix the problem.
- 5. Replace negative battery cable.
First steps
You can buy a new battery and after a while find that it is already dead or damaged. Although this can be due to several reasons, it is mainly due to parasitic runoff.
I will explain in detail what it is and why it is important to do a battery discharge test to avoid any inconvenience and cost.
What is parasitic drainage?
Essentially, the car continues to draw power from the battery terminals even when the engine is off. This may be due to many reasons. Since most cars today have many advanced auto parts and electrical parts, a small amount of parasitic drain is usually expected.
Parasitic discharge of the battery shortens the battery life. This is because it causes the voltage to drop over time. That's why your battery runs out after a while and the engine won't start.
Luckily, battery drain is a problem that can be fixed at home at no extra cost.
How many volts should a car battery have?
New and fully charged car batteries should have a voltage of 12.6 volts. This is the standard voltage for all batteries. If your car does not start well after turning the key, then your battery is dead and most likely needs to be replaced.
New car batteries can be purchased at an auto parts store near you or a trusted online store. (1)
Below is a list of everything you need to test for battery drain.
What you need
To make a simple drain test, you will need the following items:
- Digital multimeter. It must measure at least 20 amps. You can purchase it from your nearest online store or auto parts store. I recommend choosing branded multimeters, as this guarantees the quality of the multimeter.
- Wrench - removes the battery terminals, checking for battery discharge. Sizes may include 8 and 10 millimeters.
- Pliers are for removing the fuse from the battery fuse panel.
How to check the discharge of a car battery with a multimeter
You will need to follow these simple steps correctly to avoid costly mistakes.
To begin this process, you must first turn off the engine and remove the key from the ignition.
Open the hood of your car. Turn off all electrical equipment that can be turned on. These include a radio and a heater/air conditioner. Some of these systems can cause spurious rendering and should be disabled first.
Then follow these steps:
Step 1 Remove the negative battery cable.
You will need to remove the negative cable from the battery terminal. This is to prevent the battery from shorting out if you are testing from the positive end.
The negative cable is usually black. Sometimes you may need to use a wrench to unscrew the cable.
Step 2: Check the tension on the negative cable and battery terminals.
After that, you connect the multimeter to the negative cable that you unscrewed.
To set up the multimeter, you connect the black lead to the multimeter's common input, labeled (COM). The red probe enters the amplifier inlet (A).
To get correct results, I recommend that you purchase a multimeter that can record readings up to 20 amps. This is because a fully charged battery will show 12.6 volts. Then set the dial to the amp reading.
After setting up the multimeter, place the red test lead through the metal part of the negative battery terminal. The black probe will go into the battery terminal.
If the multimeter reads about 50mA, your vehicle's battery is dead.
3. Remove and replace fuses.
One of the most common methods for checking for battery parasitic discharge is to remove all fuses and replace them one at a time. This is done while still checking the readings of the multimeter.
Notice any drop in the multimeter reading. A fuse that causes the multimeter reading to drop causes parasitic discharge of the battery.
You will need to remove the fuse and replace it with a different one if you are sure it is causing parasitic leakage. If this is the only leaking component, you can remove it and reconnect the battery.
4. Isolate and fix the problem
If you remove a fuse or circuit and find that it is causing the problem, you can narrow down the problem and fix it. You can remove individual components if it is a whole circuit by checking the dip of the multimeter.
You may want to refer to the manufacturer's drawings to find out where each component is located.
Once you identify the problem, you can fix it yourself or, if you're unsure, hire a mechanic to fix it for you. In most cases, you can solve the problem by disabling the component or removing it from the system.
I recommend doing another test to see if the drain test worked and everything is working fine.
5. Replace negative battery cable.
Once you've made sure the stray outlet is gone, you can replace the battery cable with a negative terminal.
For some cars, you will have to use a wrench again to make it tight and not easy. For other vehicles, replace the cable to the terminal and cover.
Test Comparison
While there are many tests to test a battery, I recommend using the multimeter method. This is because it is simple and easy to perform. Another method using ampere clamps is handy for measuring small battery voltages.
Because of this, it's better to use a multimeter, as it measures a wide range of values out of range. It is also easier to purchase a multimeter in hardware stores or online stores. (2)
Summing up
If your car is having trouble starting when the ignition key is turned on, then you can check it yourself. I hope you found this article on checking battery discharge with a multimeter helpful.
You can check other related articles below. Until our next one!
- How to check the battery with a multimeter
- How to test a capacitor with a multimeter
Recommendations
(1) reliable online source - https://guides.lib.jjay.cuny.edu/c.php?g=288333&p=1922574
(2) online stores - https://smallbusiness.chron.com/advantages-online-stores-store-owners-55599.html
