Skip the auto shop - Our mechanics make house calls

Q: How Do I Check the Voltage of My Car Battery?

asked by on

How do I check the voltage of my car battery?

A: You can get a general idea as to whether yo...

You can get a general idea as to whether your battery is suspect by the voltmeter gauge in your car if it has one. These gauges are not too accurate as they are marked in wide increments and are really intended to be an indicator of the condition of your car's charging system. However, if the gauge indicates less than 12 volts when just turning the key to the "on" position (do not crank), your battery's voltage is probably too low to crank your engine.

A more accurate way to check the voltage is with a digital multimeter. These instruments can read not only DC and AC voltage, but also amperage and resistance. They are fairly inexpensive at most auto parts stores and home centers.

Safety goggles are always a good idea when checking the voltage of your car. First, find your battery, which may be located under the hood, in the trunk, or possibly under a seat inside the vehicle. Make sure that there is nothing electrical turned on in your car which will draw power from your battery. The multimeter uses 2 lead probes, one black and one red. The black lead plugs into the common or "com" jack & the red lead plugs into voltage, also known as "volts" or "V", jack. On the rotator switch of the multimeter, select DC volts. Take the red probe & touch it firmly to the "+" terminal on your battery. Take the black probe & touch it firmly to the "-" terminal on your battery. You will get a digital voltage readout to the hundredths scale (xx.xx). A sufficient voltage to crank your engine is 12.45 volts or higher. Any reading less will probably not crank your engine enough or at all. A fully charged battery will measure 12.66 volts or higher.

This test will give you the voltage of your battery at the time you actually test it. It will not indicate whether or not your battery can hold the present voltage. To get an idea as to whether your battery is still good enough to hold a charge you need to recheck the voltage after several hours. A good battery will not show an appreciable drop in voltage when you take this second reading. If you have a substantially lower reading, your battery needs replacement.

Was this answer helpful?
Recommended services
Get a Quote

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: lights won't turn off

These types of lighting malfunctions can occur if the lamp module has failed. This module generally needs to be coded by a dealer if it is replaced unless you can either locate a precoded lamp module from the dealer or...

Q: Lost all power to the car

Turning on one additional switch creating a loss of all power suggests you have a short somewhere in your system. The additional power draw that the extra fan is creating puts an additional load on voltage being supplied to other...

Q: Electrical components on the driver's side quit working

Hello there, electrical issues are not uncommon on the 2002 Mercedes CL500. There are a few potential causes such as a wiring fault, low battery, or failing components. With the fault moving from system to system, the most likely in...

Related articles

P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.