What each part does
- Battery: stores the power that starts the engine and runs the electronics while it's off.
- Starter: a small motor that uses battery power to turn the engine over.
- Alternator: once the engine runs, it makes electricity and recharges the battery.
Signs it's the battery
- Rapid clicking when you turn the key
- Dim dash lights, or none at all
- A slow, tired crank that gets slower
- The car sat for a while, or a light was left on
- It starts after a jump and keeps running fine
- It's a cold morning and the battery is three to five years old
Signs it's the alternator
- The battery warning light comes on while you're driving
- Headlights and dash lights dim or flicker with the engine running
- The car dies while driving, or soon after a jump
- A whining or grinding noise from the front of the engine
- A new battery goes dead within days
Signs it's the starter
- One loud click, and the lights stay bright
- A grinding or whirring sound, but the engine doesn't turn
- It starts sometimes and not others, with a good battery
- A jump doesn't change anything
When it's none of the three
If the engine cranks normally but won't fire, the battery and starter are doing their jobs. The problem is more likely fuel, ignition or a sensor, and the car needs a mechanic. That's a tow to your shop, not a jump.
What a jump start tells you
- It starts and keeps running: most likely the battery. Drive at least 20 to 30 minutes, then have the battery tested.
- It starts, then dies within minutes: most likely the alternator. Don't count on getting far; arrange a tow to a shop.
- Nothing changes: most likely the starter, a bad connection, or something else. It needs a shop.
Our jump start service is $65 plus $3 a mile for the drive to you, and if the jump doesn't work, the same truck can tow the car on the same call.
Get it tested
Many auto parts stores test batteries and charging systems for free. A test tells you whether the battery holds a charge and whether the alternator is putting out the right voltage. Don't replace parts on a guess.
A note on safety
Never jump a battery that's cracked, swollen, leaking, frozen or smells like rotten eggs. Keep sparks and flames away from the battery, and if you're not comfortable connecting cables, call for help. See how long a jump start takes for what to expect.