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Every car has a battery because it would go nowhere if it didn’t. And those enrage-inducing moments when you crank the key and hear nothing but a click always happen when you least expect it. We’ll show you how to use a multimeter to check a car battery do a few battery tests so you can figure out what’s wrong.

What is the ideal voltage for a car battery?
The voltage of a good automobile battery should be around 12.6 volts. It’s crucial to test the battery after it’s been sitting for at least an hour to determine what’s known as the’resting voltage.’ If you’ve been driving recently (and the charging mechanism is working properly), the battery is likely to produce a greater number than the resting voltage, which could be misleading.

Better yet, leave the car overnight and test the battery the next morning to receive a more accurate picture of the charge state.

It’s simple to test a battery with a multimeter. The first step is to ensure that you have access to the battery terminals (the metal connections on the top or front of the battery).

Batteries are usually found on one side of the engine in the engine bay. Consult the owner’s manual if the battery is not visible when you open the hood. In most current cars, the battery is protected by a plastic cover that can unclip, hinge up, or be removed with a few nuts or screws. There may also be a red cover that lifts off or snaps open over the positive (+) terminal.

When the battery is exposed, be sure nothing metal touches the terminals and produces a short, so don’t place wrenches or other tools on top of it.

How to use a multimeter to test a car battery
The first test with your multimeter will be to measure DC voltage, which will be indicated by a solid line above a letter V and a dashed line above a letter V. Set the dial to 20, and you’ll be able to precisely measure between 0 and 20 volts.

Touch the positive (typically red) terminal with the red probe and the negative (usually black) terminal with the black probe. The + and – terminals will be labeled. If you obtain a reading with a minus in front of it (-12.6 instead of 12.6), the probes are in the wrong place!

Ideally, the resting voltage should be no less than 12.6V. A battery with a reading of 12.2V is only 50% charged and is classified as discharged below 12V.

Disconnect the battery and fully charge it using a battery charger if the multimeter shows less than 12.6 volts. Then set it aside for the night. Something is consuming the battery considerably faster than the computer memory and digital clock if it keeps a charge while it’s not linked to the automobile. However, if you try to fully charge the battery and it does not charge, you may undertake battery reconditioning with a few simple steps and materials. As usual, safety comes first. Mention that there are several types of batteries to be aware of before performing battery reconditioning. There are a number of battery reconditioning guides available online that you may learn from and use to save money before replacing your battery.
Keep in mind that even with the motor turned off, all modern cars suffer from ‘parasitic loss,’ which occurs when something electronic drains the battery. As a result, devices like the clock, computer, and alarm clock consume some power. If you feel this is causing your battery to die during storage, you should disconnect or remove it totally.

How to use a multimeter to test your alternator
An alternator is a device that generates electricity and charges a battery. Not only that, but it also takes over and supplies power to the car’s electrical systems while you’re driving.

So, while the engine is running (and keeping an eye on moving parts), use your multimeter to do the same battery test as before. At regular idle speed, a healthy charging system should read between 13.8V and 14.4V.

Anywhere outside of that range, your car is either undercharging or overcharging, both of which will reduce battery life and necessitate additional study. For more information about your car’s charging system, see

Where do you look for dead cells in a car battery?
First and foremost, knowing that a battery cell is dead is useless, much like knowing that the battery won’t hold a 12.6 volt charge because you can’t fix it. As a result, a resting voltage test is equally as good as a diagnosis.

A battery normally does not go bad all at once; instead, portions of the battery’s cells will die. When starting an engine, slow turning over is a sign of dead battery cells.

Most modern automobile batteries are sealed and maintenance-free, however some older batteries include individual cells that can be accessed. Individual caps or a plastic cover that clamps over all, or several, of the cells will be used. Make sure you don’t acquire any liquid on your skin because the cells contain a mixture of water and sulfuric acid. A hydrometer-style battery tester that detects the specific gravity of the battery acid is required to test each cell. You can detect if a cell is alive or dead by the quantity of floating balls.