Symptoms
- Unsure if the jump-start was done correctly
- Small spark or pop occurred during connection
- Battery case looks cracked, swollen, or frosty
- Cables got warm or smelled odd during use
Likely causes
- CommonGround clamp attached to the dead battery's negative terminal instead of the frameThis is a widely taught step that's easy to skip and slightly increases spark risk near the battery.
- PossibleClamps briefly touched each otherTouching the two clamps together can cause a spark or minor short.
- Less commonAttempting to jump a visibly damaged batteryA cracked, leaking, or frozen battery should never be jump-started due to explosion or acid leak risk.
What to do
- Stop and inspect the battery visually: if it's cracked, swollen, leaking, or looks frosty/frozen, do not attempt to jump it at all.
- If the battery looks fine, disconnect all cables safely, starting with the negative/ground cable.
- Redo the connection using the standard safe order and grounding the final negative clamp to unpainted metal on the engine, away from the battery.
- Check that clamps are firmly seated on bare metal and not touching each other or any other metal part.
- Keep sparks and flames away from the battery area throughout the process.
- Once started, let the car run for several minutes before turning it off again to let the alternator recharge the battery some.
Tools and parts
- Jumper cables or a jump starter pack
- Safety glasses
When to call a pro
If the battery shows any physical damage, have it replaced by a professional rather than jump-starting it.
Safety
Use caution
Never attempt to jump-start a battery that is cracked, leaking, swollen, or appears frozen; call a professional or roadside service instead.