A jump starter is a compact battery pack that can start a car with a dead 12V battery without a second vehicle or long jumper cables. If you have ever waited in a parking lot for a stranger to help, a portable jump starter is one of the most useful things you can keep in your trunk.
Quick answer: Turn the car and accessories off, connect the red clamp to the battery’s positive (+) terminal, connect the black clamp to bare metal or the negative (–) terminal, switch the jump starter on, start the engine, then remove the black clamp first and the red clamp second.
What Is a Jump Starter?
A portable car jump starter (also called a battery booster or jump box) stores energy in a lithium battery and releases a short burst of high current through clamps, just like a running car would through jumper cables. Many models also work as a power bank for phones and include an LED flashlight.
How to Use a Jump Starter in 6 Steps
- Read your manuals. Check both the vehicle owner’s manual and the jump starter instructions. Some vehicles have remote jump points under the hood.
- Turn everything off. Ignition off, headlights off, climate control off, and the jump starter switched off.
- Connect the red clamp to the positive (+) battery terminal or the positive jump post.
- Connect the black clamp to the negative (–) terminal or an unpainted metal ground point, away from the battery if your manual recommends it.
- Switch on and start. Turn the jump starter on (or press its boost button if it has one), wait for the ready light, then start the car. Do not crank for more than a few seconds at a time; let the pack rest between attempts.
- Disconnect in reverse. Once the engine is running, turn the jump starter off, remove the black clamp, then the red clamp. Let the car run or drive for a while so the alternator can recharge the battery.
Most modern jump starters have reverse-polarity and short-circuit protection, but never let the clamps touch each other while connected.
How Many Amps Does Your Jump Starter Need?
Jump starters are rated by peak amps and, more usefully, by the engine size they can start. Bigger engines and diesel engines need more power, and cold weather makes any battery harder to start.
| Vehicle | Typical choice |
|---|---|
| Compact car or small SUV (4-cylinder) | Entry-level jump starter |
| Midsize car, SUV or V6 | Mid-range model with a higher engine-size rating |
| V8 truck, large SUV or diesel | Heavy-duty model rated for your engine size |
Always buy a model whose stated gas or diesel engine limit covers your vehicle, with some headroom if you live somewhere cold. For example, the 800A car jump starter is rated for gas engines up to 6.0L and diesel engines up to 3.0L.
Jump Starter vs. Jumper Cables
- No second car needed: a portable jump starter works on its own, anywhere.
- Safer clamps: most include polarity protection, which jumper cables do not.
- Extra features: USB charging and a flashlight help in a roadside emergency.
- Must stay charged: unlike cables, a jump starter only helps if you recharge it regularly.
Jump Starter with Air Compressor: Worth It?
Dead batteries and low tires are the two most common roadside problems. A 2-in-1 jump starter with air compressor combines a battery booster and a digital tire inflator, so you carry one device instead of two. If you already own a tire inflator, a standalone jump starter is enough.
How to Keep a Jump Starter Ready
- Recharge it after every use and at least every few months, even if unused.
- Store it in the cabin or trunk away from extreme heat when possible.
- Check the charge level before long road trips and in early winter.
Prevent Dead Batteries in the First Place
If your car sits for weeks, a battery maintainer keeps the 12V battery topped up so you need the jump starter less often. See the 1500mA smart battery maintainer and the portable 12V trickle charger.
Shop the Gear in This Guide
- 800A Car Jump Starter, 28,000mAh
- Jump Starter with Air Compressor & 150 PSI Tire Inflator
- 1500mA Smart 12V Battery Maintainer
- Portable Tire Inflator, 120 PSI
See more roadside tools in our Car Accessories collection, or read our car gadgets guide and portable tire inflator guide.
Frequently Asked Questions
Can a jump starter damage my car?
Used correctly, no. Connect red to positive and black to negative or ground, keep the clamps apart, and follow the vehicle manual. Polarity protection on most units adds a safety margin.
Which clamp goes on first?
Red (positive) first, then black (negative or ground). Remove them in reverse: black first, then red.
How long does a jump starter hold a charge?
Many lithium units hold a usable charge for months, but recharge every few months and after each use so it is ready.
Can I use a jump starter on an EV?
EVs still have a 12V battery that can go flat. Some automakers allow jump-starting the 12V system and some do not, so follow your EV owner’s manual exactly.
Why won’t my car start even with a jump starter?
The battery may be completely failed, the jump starter may be undercharged or too small for the engine, or the problem may be the starter or alternator rather than the battery.