You can jump start a car with a portable battery pack (lithium jump starter) in under two minutes, with no second vehicle needed: connect red to the positive terminal, black to a metal ground, power on the pack, and start the engine. A portable jump starter is the fastest, safest way to get moving after a dead battery.
What you need
A charged lithium jump starter sized for your engine. Rough guide: 4-cylinder gas engines start easily with an 800 Amp Jump Starter; V6/V8 and small diesels want the 1500 Amp or 2000 Amp models. Keep the pack charged so it's ready when you need it.
Step-by-step
- Turn everything off — ignition, lights, accessories. Put the car in Park.
- Connect the red (+) clamp to the battery's positive terminal.
- Connect the black (–) clamp to a clean, unpainted metal ground on the engine block or chassis — not the negative battery terminal.
- Power on the jump starter (Battery Tender® packs stay off until you switch them on, so the clamps are safe to attach).
- Start the engine. Crank in short bursts of 3–5 seconds. If it doesn't fire, wait 30 seconds and try again.
- Once running, remove the black clamp first, then the red, and recharge the pack.
Safety notes
Never touch the clamps together when the pack is on. If you see corrosion, leaking, or smell rotten eggs, stop — the battery may be damaged. Reverse-polarity and spark protection on Battery Tender® jump starters guard against the most common mistakes.
Recommended Battery Tender® products
Compare sizes in Jump Starters. For roadside kits, the 800 Amp Jump Starter + Tire Inflator covers a dead battery and a flat tire in one device. After a jump, a smart charger like the Plus 12V 1.25A Maintainer fully recharges the car battery.
Frequently asked questions
How many amps do I need to jump start a car?
About 400–600 cranking amps for most 4-cylinders; 1,000–2,000 for V6/V8 and diesels.
Do I connect the black clamp to the battery?
Connect it to a clean metal ground on the engine or chassis, not the negative post — this reduces spark risk near the battery.
Can a battery pack jump start a completely dead battery?
Yes — a portable lithium jump starter delivers cranking power independent of the car's dead battery.
How long should I let the car run after a jump?
Drive or idle at least 20–30 minutes so the alternator can recharge the battery; better yet, finish the recharge with a smart charger.
Why won't my car start even with a jump starter?
If it cranks but won't fire, the issue may be fuel, starter, or ignition — not the battery. If it doesn't crank at all, check clamp connections and pack charge.
Related Battery Tender® guides: Automotive battery guides · EV guides (EVs have a 12V accessory battery that can die too) · Power inverter sizing.
