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Car Battery Tester – Test Your Car Battery


Car Battery Tester
In the market today, there are many types of car battery tester available from the cheapest $10 up to few hundred dollars. The reason some battery testers with higher price tag is they have extra capabilities including higher measurement range, bad cell detection, high/low voltage to test both the battery and starter. Some advance tester provide high amp charging function and engine start assistance too. However, as a normal user, we normally just need a battery tester that shows the available voltage power.

Here we have go a cheap car battery tester (you can called it voltmeter or volt gauge) purchased from Autobacs. It cost $22 dollars and we got it for $7 during a sales promotion. This gauge comes with a digital reading, a protective cover, and a universal car cigarette lighter power plug and lead wire. We recommend using this voltmeter to test your car battery because you don’t have to care about the DC or AC reading and you don’t even need to open up your car hood. It is 100% safe for people who know nothing about cars. Moreover, the digital reading is more accurate and easy-to-read.

When you need to test your car battery

In many situations you will need to test and check if your car battery is healthy/dead/going to die. It is recommended to test the battery when:

  • Your car engine is hard to start. It has to be cranked several times before it is able to run.
  • Your car engine won’t start especially in the morning and it has not been start for a certain period of time (usually is > 12 hours).
  • Your car has failed to start recently and always needs a jump starts.
  • Your car battery is old. It is either more than a year or has covered its warranty. Generally, most car batteries come with at least one-year warranty. Some batteries such as EverStart do provide a two-year warranty while some come with a three-year free replacement warranty. See Walmart car battery prices if you have recently purchased one from them.
  • You have recently added some car accessories that require more voltage from your car battery, for example, audio system with amplifier, subwoofer, and loudspeaker.

How to test a car battery

It is very simple and straight-forward to use the $22 voltmeter to test a car battery. Connect the cigarette lighter power plug to your car cigarette lighter socket. The socket is usually ships with a plastic dummy plug. If you are using a dedicated car battery tester, connect the red lead to positive battery terminal (+ve), black lead to negative battery terminal (-ve). Make sure leads are connected to the battery terminal correctly. There are two things to test the health of a car battery.

1. Measure the open circuit voltage 

Leave your car over night or more than 12 hours to have a more accurate test result. Make sure nothing has been left on (lights, stereo, or any component that will drain the battery). Measure the open circuit voltage before starting the engine. The reading of a standard 12 V (Volt) car battery should be as follow:

Open Circuit Voltage Approximate Charge Description
12.60 100% (Fully Charged) Battery is Healthy
12.35 75% Battery is Good
12.10 50% Battery is OK
11.95 25% Battery is Not So Healthy
11.70 0% (Discharged)

Table: Car Battery Voltage

The tolerance of checking is +-0.2 V (Volt) because open circuit voltage is often affected by temperature. This is because the voltage will be slightly lower when the temperature is low. Also, standard flooded lead-acid battery and maintenance-free battery has slightly different readings.

If the battery voltage is lower than 10, it could be a fault with the charging system or the battery itself is dead. In this case, a jump start will help you to start the car but the battery will not be recharged if it is dead. Do check the fluid level if you are using a standard lead-acid battery.

2. Start the car and test the battery

Now start the car and read the voltage. A car’s charging system basically provides a fixed voltage of typically in between 13.8 and 14.4 V (Volt). If the reading is lower than 13 V, it could mean a fault with the charging system. On the other hand, if the reading is > 14.5 V (Volt), it means the charging system is providing too much of power to the battery. Overcharge could cause an explosion. Again, a tolerance of checking is +-0.2 V because every charging system could be different. For more details, see the video of how to test a car battery.

We strongly suggest you to check your car battery from time to time to make sure it is healthy. You can get a voltmeter (same with the one we are showing here) for less than $10 and fix it in your dashboard easily. It is one cheapest car battery tester you can find from many car accessories shop.