How to Use a Jump Charger to Charge Car Batteries

by Jerry Garner
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battery charger image by Albert Lozano from

A jump charger, or jump box, is a portable device that can restart a car that has a dead battery. A jump charger is essentially a portable battery with jump cables built into it, so you can use it in the same way you would use a running car to jump start your dead battery. Once you restart your car with a jump charger, you simply let the engine run to recharge the battery fully.

Step 1

Park the car and set the parking brake. Turn off the air conditioner, radio and all lights. Pop the hood latch and raise the hood to gain access to the battery. Batteries may be housed in different locations in cars. If the battery in your car is not immediately visible, refer to your owner manual to locate the battery compartment.

Step 2

Check the battery cells. If your car's battery died because of a drain on power from leaving your keys in the ignition or the lights turned on, then a simple jump will fix your problem. However, if the cause of your dead battery is not obvious, you may first need to refill the cells of the battery. Using a screwdriver, lift the cell covers. Look inside the cells to see if the water level is low. There is no fill line in most batteries, but the water should reach the top of the cell. If the water is low, pour water into the battery cells one at a time. Replace all cell covers.

Step 3

Connect the terminals. Connect the red terminal clamp from the jump charger to the positive terminal post on your car's battery. The positive post will be labeled with a plus sign, a red marking, or both. Connect the black terminal clamp from the jump charger to the negative battery post. The negative post will be labeled with a minus sign, a black marking, or both.

Step 4

Restart the battery. With the cables connected, turn on the jump charger by flipping or turning on the power switch. The electric circuit from the jump charger to the car battery is now active. Start the engine of your car. You may have to make two or three attempts before the engine starts, as it can take time for power to transfer into the car battery.

Step 5

With your car still running, turn the jump charger off and disconnect the cables. Remove the cables in the reverse order you used to attach them; remove the black clamp from the negative post first, then remove the red clamp from the positive post. Close the hood. Allow the car to run for at least 30 minutes to charge the battery fully.

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