#Digital 12 volt battery meter how to#

So, systems such as the clock, computer and alarm use some power. One thing to bear in mind is that all modern cars experience 'parasitic loss', which is when something electrical drains the battery even with the engine turned off. A battery that reads 12.2V is actually only 50% charged, and is classed as discharged below 12V. The resting voltage should ideally be no lower than 12.6V. If you get a reading with a minus in front of it (-12.6 rather than 12.6) you've got the probes the wrong way round! Touch the red probe to the positive (usually red) terminal, and the black probe to the negative (black) terminal.

Set the dial to 20, which will allow you to accurately measure between 0-20 Volts. The first test with your multimeter will measure DC voltage, indicated with a solid line and a dashed line above a letter V.

#Digital 12 volt battery meter how to#

Jump starting a battery: the right and wrong ways to do it How to check a car battery with a multimeter Once the battery is exposed, be extremely careful that nothing metal touches the terminals and causes a short, so don't rest wrenches or other tools on top of the battery. There may also be a red cover over the positive (+) terminal that will lift off or snap open, too. In modern cars, the battery will often have a plastic cover which will unclip, hinge up, or occasionally require removing with a few bolts or screws. The alternator’s job is to generate energy to feed the electrical system and charge the battery while the vehicle is running.Using a multimeter to test a battery is easy. The first thing to do is make sure you can access the battery terminals (the metal connections on the top or front of the battery).īatteries are commonly located in the engine bay to one side of the engine. If the battery is not immediately obvious when you open the hood, consult the owner's manual. Dropping below 14 means either the battery is weak and unreliable for sustained vehicle operation or the alternator is failing. With the motor running, the multimeter rating should stay in the 14 to 14.5 volt range. Immediately following the crank cycle, the vehicle will begin to idle and maintain a steady draw from the battery. Again, in this case, recharge or replacement of the battery may be necessary. If it falls below 10 volts, it means the battery does not have sufficient turnover strength and is prone to failure. As soon as the car is turned on, the voltage reading will drop for a quick moment, but should not fall below 10 volts. To get this reading, a second person will be needed for the purpose of starting the ignition. This is the moment that the vehicle is turned on and the battery is under the most draw because of the higher amount of energy needed to drive the starter motor. Once the resting voltage has been determined, it is time to get a reading on the crank cycle. If the measured reading is less than 12.2 volts, the battery’s resting voltage is weak, which means it most likely needs to be charged or replaced. This voltage range means the battery is in good condition for starting the vehicle.

When the probes touch the terminals while the car is off and the battery is resting, the multimeter display should show a reading of 12.2 to 12.6 volts (full charge). The red probe is for contact with the positive terminal and the black probe is for contact with the negative terminal. For measuring battery load, the multimeter has two probes: red and black.