Jump Starter Guide: What to Check and How to Connect One Safely

A portable jump starter can get a dead battery going without a second vehicle. The rules for using one come from the manufacturer, so this guide uses NOCO's published instructions as an example of what a maker tells you. Other brands have their own rules, so always read the manual that comes with yours. Each fact has a numbered source at the bottom of the page.

Start with the manuals

NOCO's user guide for its GB40 jump starter tells readers to read the vehicle owner's manual for specific precautions and recommended jump-starting methods, and to confirm the battery's voltage and chemistry before connecting.^[1] The GB40 is for 12-volt lead-acid batteries only.^[1]

The takeaway for shopping is to match the jump starter to your battery. Check the voltage and battery type the maker lists, and compare them with the battery you plan to start.

Connecting it: NOCO's steps

NOCO's support page for its Boost jump starters gives these steps:^[2]

Connect the positive (red) clamp to the positive terminal on the battery first.
Connect the negative (black) clamp to a chassis ground, which NOCO describes as an unpainted metal surface or bolt on the engine block, away from the battery and fuel lines.
Press the power button on the Boost and wait for the lights to show that it has detected a safe connection.

The GB40 user guide adds more detail.^[1]

Don't connect to the carburetor, fuel lines or thin sheet-metal parts.
Turn off the vehicle's power loads, such as headlights, radio and air conditioning, before jump starting.
When disconnecting, work in the reverse order and remove the negative clamp first.

Limits to know about

These limits are from the GB40 user guide and apply to that model. Other models will differ.^[1]

If the vehicle doesn't start right away, wait 20 to 30 seconds and try again. Don't attempt more than five consecutive jump starts within fifteen minutes, then let the unit rest for fifteen minutes.
Don't try to jump start a damaged or frozen battery.
The GB40 is designed to work in ambient temperatures from -20°C to 50°C (-4°F to 122°F).

What to check on the listing

Voltage and battery type. Does the listing say it is for the voltage and battery chemistry you have?
Engine fit. Does the maker say it supports your engine type and size? Treat the amp rating as the maker's rating, and compare it with what the maker says it supports.
What's in the box. Look for clamps, a charging cable and a carry case in the listing.
Charging. Check how the unit is recharged and keep it charged for when you need it.

Jump starter deals on the board right now

These are the sale prices we checked on each retailer's page when the board was last updated (Oct 27, 2026, 5:36 AM ET). Prices change quickly, so confirm the price in the retailer's cart.