How to Jump-Start a Lithium Battery Safely

What You’ll Need

A lithium jump starter rated for your vehicle’s voltage and engine size, with its manufacturer-approved cables and clamps.
Your vehicle owner’s manual, which identifies the approved jump-start points and any restrictions for its battery system.
Safety glasses and insulated gloves if available. Remove metal jewelry, and keep the work area dry, well ventilated, and away from flames or sparks.

This guide covers a vehicle with a conventional 12-volt starting system. Some vehicles use a 12-volt lithium auxiliary battery, a high-voltage traction battery, or a battery-management system with special procedures. Do not assume these systems can be jumped the same way. Follow the vehicle maker’s instructions or call roadside assistance when the correct method is unclear.

Step-by-Step

Confirm the battery type. Read the vehicle and jump-starter manuals. Verify that the starter supports the vehicle’s nominal voltage and intended battery chemistry, and that its rated capacity suits the engine. “Lithium” can describe different battery chemistries; a lithium jump pack is not automatically suitable for every lithium vehicle battery. If the manual prohibits jump-starting or specifies a different procedure, stop and follow it.
Check for damage and danger. Do not jump a battery that is cracked, leaking, swollen, unusually hot, emitting an odor, or otherwise damaged. Do not proceed if cables are frayed, clamps are damaged, or the jump pack is wet. Move away and seek professional help if the battery is smoking, hissing, or heating rapidly. Never try to charge or jump a frozen battery.
Prepare the vehicle. Park on a stable surface away from traffic, set the parking brake, switch off the ignition and electrical accessories, and remove the key or keep the key fob away as the manual directs. Put the transmission in Park or Neutral. Keep people clear of moving parts and make sure the vehicle cannot roll.
Locate the designated connection points. Open the hood and use the marked positive jump terminal and the specified ground point, if the vehicle provides them. Some cars have the battery in the trunk or under a seat; the under-hood posts may still be the required points. Do not guess based on cable color or connect to an arbitrary bolt. Avoid high-voltage components, fuel lines, and moving parts.
Check the jump pack. Make sure it is switched off before attaching clamps, and confirm it has enough charge according to its indicators and manual. Put it on a stable, dry surface where cables cannot touch fans, belts, or hot parts. If its instructions require a particular mode or sequence, follow those directions exactly.
Attach the positive clamp. Connect the red positive clamp to the vehicle’s designated positive terminal. Make sure it grips clean metal and cannot slip off. Keep the clamp away from the negative terminal and nearby metal.
Attach the negative clamp. Connect the black negative clamp to the vehicle’s specified grounding point, if instructed. If the vehicle manual instead directs you to the battery’s negative post, use that point. Never let the clamps touch each other, and do not reverse the connections. Stop if the markings are unclear.
Enable the jump starter. Switch it on or activate its boost function only as directed by its manual. Some devices require an indicator confirmation before attempting to start; others have an automatic protection system. Do not bypass a warning, force a boost mode, or continue if the pack signals reversed polarity or another fault.
Attempt to start briefly. Start the vehicle using its normal procedure. If it does not start promptly, stop cranking and wait for the interval specified by both manuals before trying again. Repeated long attempts can overheat the starter, cables, or jump pack. Do not exceed the device’s allowed number or duration of attempts.
Disconnect in the stated order. Once the engine is running, switch off the jump starter if its instructions say to do so. Remove the clamps in the sequence specified by the vehicle and pack manuals, keeping them apart and away from metal. A common sequence is negative first, then positive, but follow the instructions for your specific setup. Stow the pack and cables securely.
Check the vehicle afterward. Keep the engine running only if the owner’s manual permits it, and drive or arrange service as the manufacturer recommends. A jump-start is not a repair or a dependable battery recharge. If the battery warning remains on, the vehicle stalls, or it will not restart, arrange a battery and charging-system check. Have a qualified technician inspect a lithium battery system if its condition is uncertain.

Common Mistakes

Using a donor car by default: A lithium jump pack and a second vehicle are not interchangeable methods. Connecting one vehicle to another can damage sensitive electronics or lithium battery systems. Use a donor vehicle only when the vehicle maker explicitly approves that exact procedure.
Guessing at terminals: Battery location and grounding arrangements vary. Connecting to the wrong post or an unsuitable ground can cause arcing, damage, or injury. Find the marked points in the manual before attaching anything.
Ignoring chemistry or voltage: A pack that fits physically may still be electrically unsuitable. Match the device to the vehicle’s specified system and battery type.
Reversing clamps or letting them meet: Incorrect polarity can damage electronics and create sparks. Keep the pack off while connecting, check the positive and negative markings, and never allow the clamps to touch.
Forcing repeated starts: Long or frequent cranking attempts strain equipment and may hide a deeper fault. Follow the manuals’ time limits and stop if the pack overheats or reports an error.
Jumping a visibly damaged battery: A jump pack cannot make a damaged or unsafe battery safe. Do not handle a battery that is swollen, leaking, smoking, or unusually hot.

Tips

Read the manuals before an emergency and keep the vehicle’s jump-start instructions accessible.
Inspect the jump pack and leads periodically. Recharge and store the pack within the temperature and charge range specified by its manufacturer.
Use only the supplied or explicitly approved cables and accessories. Do not splice leads or add improvised adapters.
Keep the jump pack secured in the vehicle and protected from extreme heat, moisture, and physical damage as its manual directs.
If the vehicle is a hybrid or electric model, distinguish the low-voltage auxiliary system from the high-voltage traction battery. Never attempt to jump the high-voltage battery.

Troubleshooting

The jump pack shows an error: Switch it off, check that the clamps are on the correct designated points and firmly attached, and consult the error code in the pack manual. Do not override reverse-polarity or temperature protection. If the warning remains, disconnect only as directed and stop.

The vehicle does not crank: Confirm that the pack is charged and enabled, the connections match the vehicle instructions, and the vehicle is in the required starting position. Check for a key-fob or immobilizer message. If the setup is correct but there is still no response, a starter, fuse, connection, or other fault may be involved; contact roadside assistance.

The engine cranks but will not start: The cause may not be a weak battery. Avoid repeated attempts and arrange diagnosis, especially if warning lights appear or the engine makes unusual noises.

It starts, then dies or will not restart: The battery may be unable to hold charge, or the charging system may not be working. Do not rely on another jump as a fix; have the vehicle inspected.

A clamp sparks, gets hot, or slips: Stop immediately. Do not continue trying to start the vehicle. Follow the manuals for safe disconnection; if the battery or cables appear damaged, keep clear and get professional help.

Frequently Asked Questions

Can I jump-start a lithium battery with another car?

Do not assume that is safe. Use a donor vehicle only if the vehicle manufacturer explicitly approves the method for that vehicle and battery system. A compatible, protected lithium jump starter is often the specified option.

Can I use any lithium jump starter?

No. The pack must match the vehicle’s voltage and be approved for the relevant battery type and engine. Check both manuals rather than relying only on a product’s general description.

How long should I leave the jump starter connected?

There is no universal wait time. Follow the pack and vehicle instructions for connection, activation, and start attempts; do not leave it connected longer than directed.

Will jump-starting recharge the battery?

It may provide enough power to start the vehicle, but it does not reliably restore a depleted or failing battery. Use the charging method approved by the vehicle maker, or have the battery and charging system checked.

Can I jump-start a hybrid or electric car?

Some models permit a jump-start of the low-voltage auxiliary battery using designated points, while others have special restrictions. Follow the owner’s manual and never connect a jump pack to the high-voltage traction battery.

What if the battery is swollen or leaking?

Do not jump, charge, or handle it. Keep away from the vehicle’s battery area and contact roadside assistance or a qualified technician for safe help.

Further reading: National Highway Traffic Safety Administration. Details can change, so check the official page for anything that matters to you. Spotted a mistake? Tell us. How we write an answer.