How to Jump a Car With a Battery Pack

Updated: Apr. 05, 2024

Traditional jumpstarts can cause electrical problems in newer cars. Using a car jump starter will alleviate that worry. Here's how.

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30 minutes




Around $75


Dead battery? No problem! Here's how to jump a car with a battery pack in a few simple steps and get back on the road in no time.

Tools Required

  • Jumper Pack

Benefits of a car battery jump pack

You probably keep jumper cables in your vehicle so you can solicit a jump if your car battery dies or offer a jump to a fellow driver. But jumping batteries on cars built after 2000 might not be so smart. Newer vehicles can contain dozens of computers and even more digital devices. Jump-starting a car with cables connected to a running vehicle can create a voltage spike of up to 15.5 volts and fry expensive computers in both vehicles involved. Most of these components communicate on a shared data bus, so surge damage to just one computer or digital device (even a radio) can disable the entire data bus, preventing the vehicle from starting and costing hundreds to diagnose and repair.

Jump-starting with a jumper pack (also called a jump starter, booster pack, or a juice pack) is a better alternative. The battery inside the jumper pack boosts the dead battery at a safe voltage. When used properly, a jumper pack is the safest way to protect the electronics in the dead vehicle while providing enough boost to get the engine running.

Project step-by-step (8)

Step 1

Choose a jumper pack

To choose a jumper pack, ignore the pack’s peak amp rating. Peak amps don’t indicate the pack’s ability to start a vehicle. Instead, look for the unit’s cranking amps (CA) rating. You need a minimum of 225 CAs to start a four- or six-cylinder engine. If you have a larger engine or want more power, find a pack with 400 or more CAs.

Another thing to consider is the type of car battery you have. The two main options are lead acid and lithium batteries. Lead acid batteries are usually cheap and powerful but tend to be bulkier and lose their charge fast, requiring frequent recharging. Lithium batteries are smaller and last longer when fully charged, which means they can sit in your car longer without needing a recharge. The biggest downside is that they can be more expensive.

How To Jump A Car With A Battery Pack Choose a jumper packTMB Studio

Step 2

Turn everything off in the dead vehicle

Before using a jump box or jumper pack, turn off all lights and electrical accessories in the dead vehicle.

Step 3

Connect jumper

Next, connect the cables just as you would ordinary jumper cables—positive clamp to the positive battery post and negative clamp to the negative battery post or a metallic engine component or chassis grounding point.

How To Jump A Car With A Battery Pack Connect jumperTMB Studio

Step 4

Try starting the vehicle

Then try starting the vehicle. Follow the jumper pack instructions for maximum cranking times.

If the jump works, you’re all set. If not, it might be time to call a pro or replace your battery. At least you didn’t damage any electronics while trying to jump the car.

Step 5

Remove jumper cables

When disconnecting, make sure to go in reverse order. Remove negative clamp and then positive.

Step 6

Charge jump starter

Jumper packs require regular recharging. You can’t charge a pack, throw it in your car’s emergency kit and expect it to work when you need it. Recommendations vary, but count on routinely recharging a jumper pack. If you don’t keep the pack charged, its battery will degrade to the point that it won’t accept or hold a charge. Then you’ll have to buy a new battery, which costs almost as much as a pack. However, if you maintain it properly, it’ll last for several years.

Step 7

When to call a pro

If the car doesn’t start after trying to jump-start it, it might mean it’s time to call your local car mechanic. Your battery might need to be replaced or there might be other issues that are causing your car not to turn over.

Step 8


What is the difference between peak amps and cranking amps?

Many manufacturers list a peak amp rating on their pack. But it’s not a reliable indicator of battery power. Instead, check for the pack’s cranking amps (CA) rating. To arrive at the CA rating, the battery is discharged for 30 seconds. The number of amps the battery delivers during that period while still maintaining at least 1.2 volts per cell is its CA rating. The higher the CA, the better the battery.

Can a battery be so dead it won’t jump start?

Yes. If the battery is completely dead, it won’t jump start. Therefore, you will be required to replace the car battery.

How long do I leave my car running after jump starting?

Once you jump start the car, let it run for about 15 minutes or more so that the alternator can recharge the battery.