Before You Jump: Check These First

Not every dead car needs a jumpstart. A few quick checks first:

  • Is the battery the problem? If you turn the key and hear nothing at all (no click, no crank), the battery is likely completely dead or there's a connection problem. If you hear rapid clicking, the battery is low but not dead — a jumpstart should work. If it cranks but won't fire, the battery is fine — the problem is fuel, ignition, or mechanical.
  • Check for corrosion at the battery terminals. White or blue-green buildup on the terminals prevents good contact. Clean with a wire brush before connecting cables — a corroded connection delivers insufficient current and the jump won't work.
  • Check for obvious damage. If the battery case is cracked, bulging, or leaking fluid, do not jump it — the battery needs replacement, not a jump. A swollen battery is a fire and explosion risk.

What You'll Need

  • Jumper cables — minimum 10-gauge wire, 12–20 feet long. Thin cables (16-gauge) may not carry enough current for larger vehicles.
  • A working donor vehicle — ideally with a similar or larger battery capacity than your vehicle. Using a compact car to jump a large truck can be done but may take longer.
  • OR a portable jump starter pack — lithium jump starter packs (Noco Boost, Antigravity) are compact, powerful, and let you jump your own car without a second vehicle. Highly recommended to keep in every vehicle.

Safety Precautions for Modern Vehicles

Modern cars have multiple sensitive electronic control units (ECUs) connected to the electrical system. A voltage spike from an improperly connected jumpstart can damage:

  • The Engine Control Module (ECM)
  • The Body Control Module (BCM)
  • The transmission control unit
  • Advanced driver assistance system sensors

The correct cable connection sequence minimizes voltage spikes. Follow it exactly.

⚠️ Check your owner's manual first. Some vehicles (particularly European luxury vehicles — BMW, Mercedes, Audi, Porsche) have specific jumpstart procedures or dedicated jump terminals that differ from standard procedure. Always check your manual if you're unsure.

Step-by-Step Jumpstart Procedure

Position the donor vehicle close enough to connect cables but ensure the vehicles do not touch each other. Turn off the donor vehicle before connecting cables if possible (some modern vehicles require it running — check your manual).

The Correct Connection Sequence (Memorize This)

  1. Red cable → Dead battery positive (+) — Connect the red (positive) clamp to the positive terminal of the dead battery. Positive terminals are typically marked with a "+" symbol and a red cover.
  2. Red cable → Donor battery positive (+) — Connect the other end of the red cable to the positive terminal of the donor vehicle's battery.
  3. Black cable → Donor battery negative (–) — Connect the black (negative) clamp to the negative terminal of the donor vehicle's battery.
  4. Black cable → Unpainted metal ground on dead vehicle — Connect the final black clamp to an unpainted metal surface on the dead vehicle's engine block or chassis — NOT to the negative battery terminal. A bolt on the engine block or a bracket works well. This last connection completes the circuit away from the battery, reducing spark risk near the battery (batteries can release hydrogen gas).

The sequence is: Red dead → Red donor → Black donor → Black ground (on dead vehicle). This is critical — connecting in the wrong order can create dangerous sparks and may damage electronics.

Start the Vehicles

  1. With cables connected, start the donor vehicle and let it run for 2–3 minutes. This allows the donor battery to transfer some charge to the dead battery before you attempt to start.
  2. Attempt to start the dead vehicle. If it doesn't start, wait another 2–3 minutes and try again. If it still doesn't start after 3 attempts, the battery may be too far gone or the problem may not be the battery.
  3. Once the dead vehicle starts, leave both vehicles running.

Disconnect in Reverse Order

  1. Black cable from the ground on the previously-dead vehicle
  2. Black cable from the donor vehicle's negative terminal
  3. Red cable from the donor vehicle's positive terminal
  4. Red cable from the previously-dead vehicle's positive terminal

After the Jump: What to Do Next

A successful jumpstart doesn't mean your battery is fine. It means you have enough charge to get the engine running. The charging system will now work to recharge the battery — but only while the engine is running.

Drive for at least 30 minutes on the highway (not stop-and-go city driving) to allow the alternator to substantially recharge the battery. Short city trips don't provide enough charging time and the battery may be dead again the next morning.

Get the battery tested. Any auto parts store (AutoZone, O'Reilly, Advance) will test your battery and charging system for free. A battery that needed jumping may have reached end of life — the test will tell you whether replacement is needed. Car batteries typically last 3–5 years.

When to Skip the Jumpstart and Call a Tow Truck

Some situations call for a tow rather than a jumpstart:

  • Battery jumped but car dies immediately: If the engine runs while cables are attached but dies as soon as you disconnect, the battery is fully failed and won't hold a charge — it needs replacement, not more jumping.
  • Battery has been jumped multiple times: If this is the third or fourth time in a week, the battery is at end of life or there's a parasitic drain problem (something drawing power when the car is off). Get it diagnosed.
  • Swollen, cracked, or leaking battery: Do not jump. The battery must be replaced before the vehicle is driven.
  • Engine cranks but won't start: This isn't a battery problem. It could be a fuel delivery issue, a bad fuel pump, a failed ignition component, or a mechanical problem. A tow to a mechanic is the right call.
  • Warning lights after jumpstart: If you see check engine lights, airbag warning lights, or other unexpected warning lights after a jumpstart, have the vehicle scanned for fault codes before driving further. Some may resolve on their own; others indicate real issues.
  • No safe place to perform the jump: If you're on the shoulder of a busy freeway in the dark, calling for roadside assistance or a tow is safer than attempting a roadside jumpstart.

Portable Jump Starters: The Better Option

A lithium portable jump starter (Noco Boost Pro, Antigravity Micro-Start, DBPOWER) is one of the best items to carry in your vehicle. They:

  • Don't require a second vehicle — you can jump yourself
  • Are compact enough to fit in a glove box
  • Hold charge for months without needing recharging
  • Can also charge phones and USB devices
  • Have built-in safety circuits that prevent reverse polarity damage

A quality unit runs $60–$120 and can start most passenger vehicles and even light trucks multiple times on a single charge. The best roadside insurance you can buy for under $100.

Find Roadside Assistance in Salt Lake City →