How to Efficiently Charge a Car Battery

Without a charged battery, your vehicle won't get you anywhere. Learn all about how to charge a battery so you don't get stranded.

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Without a working battery, your car won't start, leaving you stuck at home or stranded on the road. Car batteries are charged by an alternator that produces electricity while the car's running. Still, batteries sometimes lose some or all of their charge. You'll know when this happens because your car either won't start, or the starter motor will only turn over weakly when you turn the key.

Lots of short trips, or electrical components such as lights and radios left on for long periods while the car's not running are some of the most common reasons why a battery loses its charge. Battery issues happen to all vehicles eventually. Learn exactly how to charge a car battery, so when yours goes dead and your car won't start, you can get up and running again fast.

Tools Required

  • Car battery charger
  • Extension cord
  • Small wire brush (optional)
  • Volt meter (optional)

Watch this video to learn how to replace a car battery:

Project step-by-step (5)

Step 1

Turn Everything Off

  • Turn off your vehicle and make sure all interior and exterior lights and all other electrical components are off.
    • Leaving these on could drain the battery faster than you’re charging it.
  • Optionally, you could use a handheld volt meter to determine your battery’s state of charge. Touching the two prongs on the volt meter to their corresponding terminals on the battery will give a voltage reading.
    • A fully charged 12-volt car battery (standard voltage) will read between 12.4 and 12.7 volts.
      • Pro tip: Anything below 12 volts is low, and there’s a good chance your car won’t start.

Volt meterRobert Maxwell for Family Handyman

Step 2

Set the Rate of Charge

  • Choose a charge rate before connecting your battery charger to the battery.
    • Simple chargers don’t allow different rates of charge, but many models do. Charge rate is expressed in amps, often starting at 2 and topping out 10.
      • Pro tip: Unless you’re in a rush, choose the slowest charge rate first. Slower charging is easier on the battery and makes overcharging less likely, especially if you don’t have a volt meter and are charging blind.
  • Set the charger to a faster setting only if you’ll be on hand to unhook the charger and try to start the vehicle fairly soon.

Charge speedRobert Maxwell for Family Handyman