How To Test A Car Battery With A Multimeter

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You depend on your vehicle for many things: the morning commute, errands, weekend fun and more. You probably don’t even think about your car battery until one morning you get in the driver’s seat, insert your ignition key, turn it and then…nothing. Or your vehicle struggles to crank over and you see the telltale dashboard warning light.

These are all common signs that your battery is dead or dying, but testing your battery can help you determine the root cause. Fortunately, you just need one tool for testing – your trusty multimeter. This handy device measures electrical voltage, continuity and resistance. To test your battery, you’ll just need to follow a few simple steps:

Set your multimeter to measure voltage, then adjust it to 20 DC volts.
Touch each multimeter probe to its correct polarity: negative with negative (black) and positive with positive (red).
Have a friend turn on your vehicle’s headlights.
After the vehicle’s turned on, check your multimeter and record the voltage reading.

A fully charged battery should measure around 12.5 volts. That value may be slightly higher or lower, depending on your outside temperature. Measurements between 12.0 and 12.5 mean your battery is partially charged. Anything below 12.0 volts and you’re in trouble – you’ll probably need to replace your battery.

How to Safely Remove a Car Battery

Finding a replacement battery is simple. Many retailers offer a free VIN lookup tool – just punch in your VIN and you’ll see your vehicle’s exact specs, which can help you locate the proper battery models that fit.

After you’ve found a new batter, removing the old one is the next key step. Remember to wear safety gloves, goggles and long sleeves during the process. Use zip ties to secure battery cables, as they contain no metal. Don’t forget to cover the battery’s positive cable with a shop towel: This prevents accidental contact with other metal. You’ll need to follow some important steps for safe battery removal:

Disconnect the negative battery cable first. This prevents unsafe and potentially life-threatening electrical discharge.
Disconnect the positive battery cable.
Remove the securing bracket. With a wrench or socket, remove the bolt or nut that holds the bracket to the vehicle.
Lift the battery carefully out and set it aside. Set the securing bracket hardware aside to avoid misplacing them.

How Much Power Do You Get From a Typical Battery Charger?

Perhaps you don’t need to replace your battery – a simple recharge may do the trick. An auto battery charger can accomplish this feat. Chargers range between 2 and 12 amps in output, but it’s wise to pick one that’s between 4 and 10 amps. High-powered chargers may damage your battery, and low-powered models can take forever to recharge it.

If you don’t already have a multimeter, now is a good time to buy one. Available in analog and digital versions, they’re easy to find. Best of all, you don’t need a super-expensive device – a basic digital model runs between $20 and $40. A trusty auto parts retailer can supply you with a dependable high-quality multimeter, an auto battery charger and other useful tools to keep your vehicle in great condition.