7 Jump Start Mistakes That Kill Your Car's Electronics

Modern cars have dozens of computers that run everything from the engine to the radio. A sloppy jump start can send voltage spikes through those computers and cause damage that costs thousands. Here's how to do it right — and what NOT to do.

Mistake #1: connecting cables while the dead car is still running. Always turn both cars fully off before attaching cables. Attaching under load creates arcs that can damage the electronics.

Mistake #2: wrong cable order. The correct order is: positive to positive on the dead battery first, then positive to positive on the donor, then negative to the donor's negative terminal, and LAST, the negative cable to an unpainted metal surface on the dead car — NOT its battery terminal. This prevents sparks near the battery's hydrogen gas.

Mistake #3: revving the donor car aggressively. Idle the donor for 2-3 minutes instead. Revving creates voltage spikes.

Mistake #4: cranking the dead car for more than 10 seconds at a time. Give it 30 seconds between attempts to cool the starter.

Mistake #5: removing cables while the engine is running. Turn off the previously dead car, then remove in exact reverse order: negative from the unpainted metal first, then negative from donor, then positives.

Mistake #6: ignoring corrosion. If the battery terminals are crusty white/green, clean them before jumping — poor contact causes arcing.

Mistake #7: jumping a battery that's actually dead-dead. If the battery won't hold a charge after a successful jump, it's not a jump-start problem, it's a battery replacement problem. Most auto parts stores test batteries for free — or our techs can test it on-site and install a new one on the spot.