How to Use a Jump Starter Safely: Step by Step

Steps come from NOCO’s GB40 guide and Clore’s JNC660 manual; AAA and Kia cover ground points and aftercare. See how we research.

If the battery might be frozen, cracked or the wrong type, read when not to jump-start a battery first.

Step by step: NOCO GB40 (lithium)

NOCO’s GB40 user guide gives this order for a negative-ground vehicle (the most common kind):

1. Plug the clamps into the GB40’s 12V OUT port.
2. Connect the red (+) clamp to the battery’s positive terminal.
3. Connect the black (-) clamp to the negative terminal or to the vehicle chassis.
4. Press the Power button. The white Boost LED means the hookup is right; the red Error LED means the clamps are reversed, so swap them.
5. Try to start the car. NOCO says some cars need the GB40 connected for up to 30 seconds first. If it doesn’t start, wait 20-30 seconds and try again.
6. Make no more than five attempts in a row within 15 minutes, then let the GB40 rest for 15 minutes.
7. Once the car runs, disconnect in reverse order: black clamp first, then red.

The guide says not to clamp onto the carburetor, fuel lines or thin sheet metal, and to reverse the sequence on a rare positive-ground vehicle. Below 2 volts the GB40 can’t detect the battery, and its Manual Override switches the protections off.

Step by step: Clore JNC660 (lead-acid)

Clore’s JNC660 operator’s manual lists these steps:

1. Work in a well-ventilated area and wear eye protection.
2. Turn the ignition off.
3. Clamp the red (+) clamp to the positive battery terminal, or to the alternate jump point the vehicle maker recommends.
4. Clamp the black (-) clamp to vehicle ground: a non-moving metal part, such as the frame.
5. Keep the cables away from belts and fans, and stay clear of the battery.
6. Start the vehicle. If it doesn’t start within 6 seconds, let the JNC660 cool for 3 minutes before trying again. Clore says skipping the cool-down can damage the unit.
7. Once it starts, remove the black clamp first and holster it, then the red clamp.

The retry rules differ: NOCO allows five tries in 15 minutes, while Clore wants a 3-minute cool-down after each failed 6-second try.

Where the black clamp goes

NOCO allows either the negative terminal or the vehicle chassis for the GB40. Clore says vehicle ground, such as the frame, for the JNC660.

Advice written for jumper cables moves the clamp away from the battery. AAA says to put the last black clamp on a ground point such as the engine block, as far from the battery as possible. Kia’s online owner’s manual says to connect the negative cable to a chassis ground under the hood, not to the dead battery.

Use the ground point your car’s owner’s manual names. If it names none, use the point your jump starter’s manual allows.

After the engine starts

• Put the clamps away. Clore says to re-wrap the cables and re-holster the clamps after every use.
• Drive the car. See does driving recharge a battery after a jump.
• Check an older battery. AAA says a battery over three years old, or one that has been struggling, likely won’t hold a charge overnight, so have the battery tested.
• Car dies again after a short drive? AAA says the alternator is likely not recharging the battery. Have the battery and charging system checked.
• Don’t recharge the JNC660 through its clamps from a running car. Clore says the alternator’s 25-125 amps overcharge the pack and may void the warranty. Use the 12V male-to-male cord its manual describes.
• Recharge the pack before you store it. See how long a jump starter holds a charge.

Then check your own pack: does your jump starter protect you if the clamps are backwards?

Sources

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• NOCO GB40 user guide and warranty (PDF)
• Clore Jump-N-Carry JNC660 operator’s manual (PDF)
• AAA: How to jump a battery and get yourself back on the road
• Kia owner’s manual: Jump starting (12V battery)