Once you’ve purchased a car battery tester, it’s time to see what condition your battery is in. Most testers will come with detailed instructions on how to operate the specific device, but here are some general steps and tips to follow.

1. Before you start to do anything, it’s always recommended to wear a pair of rubber gloves and goggles when working with your battery. Gloves and goggles will protect your hands and eyes from acid.
2. Start by making sure the ignition of your vehicle is off and all the lights on your car are turned off.
3. Connect the positive lead on your battery tester to the positive terminal on your battery.
4. Connect the negative lead on your battery tester to the negative terminal on your battery.
5. Check the voltage of your car’s battery. If it reads somewhere above 12.6 volts, then your battery is in great condition (100 percent). A voltage reading around 12.4 volts means your battery is in good condition – approximately 75 percent. A value of 12.2 volts is about 50 percent, which means readings of 12.2 volts and lower indicate a bad battery.
6. Once you’re done checking your battery state, remove the negative terminal first. If the clamps aren’t coming off easily, you will want to use a battery terminal puller to remove them.