How to Use a Battery Tender to Charge a Car Battery

by Misty S. Bledsoe
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Battery tenders are chargers that put out small amounts of electricity to a low or dead car battery that help the car battery regain a charge. They come in handy for car batteries that haven’t been used in more than a month, because batteries lose power internally when they are not used and not recharged regularly. Hooking up a battery tender should take you about 10 minutes.

Step 1

Turn off your car if it was running and remove the key from the ignition. Open the hood.

Step 2

With a adjustable wrench, remove the black (negative) battery terminal from the battery and place it aside. Remove the red (positive) battery terminal from the car battery. Place it to the side.

Step 3

Clamp the red (positive) clamp of the battery tender over the positive battery terminal so that it won’t come off without physically removing it. Since most vehicles have a negative ground, meaning part of the cord leading to the battery is attached to the frame of the vehicle, clamp the tender's black (negative) clamp to either the engine block or vehicle frame so that it does not easily come loose. Do not clip the black clamp to hoses, wires or moving parts of the engine. It is not common to have a vehicle that has a positive ground, so check your owner's manual or call a local dealer for your vehicle type and ask the repair department if you are not sure.

Step 4

Switch the amp switch on the battery tender from “2” to “6” if that particular model has one. Plug in the battery tender to an electrical outlet, using an extension cord if necessary.

Step 5

Pay attention to the light on the battery tender. If it is red, it is still charging. When it turns green, the battery is fully charged.

Step 6

Unplug the charger from the outlet. Remove the black clamp (negative) from the engine block or vehicle frame. Remove the red (positive) clamp from the battery. Place the battery tender aside.

Step 7

Place the red (positive) battery terminal to the positive of the car battery and secure with the adjustable wrench. Place the black (negative) battery terminal to the black negative of the car battery and secure it with the wrench. Make sure the connections are tight and secure. Close the hood of your vehicle.

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