A car that will not start is often blamed on the battery, but the starter can cause similar symptoms. The two parts work together, so the clues are in how the car sounds and behaves. This article helps you separate them, though a proper test at a shop is the only way to be certain.
How the battery and starter work together
The battery stores the electrical energy needed to start the car. When you turn the key or press the button, current flows to the starter, an electric motor that turns the engine until it can run on its own. Once running, the alternator takes over powering the car and recharging the battery. A problem with any of the three can look like a “won’t start.”
Signs of a weak or dead battery
- Slow, labored cranking
- Rapid clicking when you try to start
- Dim headlights and dashboard lights, or lights that dim sharply during cranking
- Electronics that behave oddly or reset
- The car starts after a jump-start or charge
- A battery that is several years old or has a history of going flat
Signs of a failing starter
- A single loud click with no cranking, while the lights stay bright
- A grinding or whirring noise when you try to start
- The starter spins but the engine does not turn
- Intermittent starting: it works fine, then fails, then works again
- Smoke or a burning smell after repeated attempts (stop and seek help)
Our car starter problems guide goes into starter symptoms and causes in more detail.
Side-by-side comparison
| Clue | Points toward battery | Points toward starter |
|---|---|---|
| Lights when you try to start | Dim or go out | Stay bright |
| Sound | Rapid clicking or slow crank | Single click, grinding or silence |
| After a jump-start | Car starts | Car still will not crank |
| After a charge | Car starts | No change |
| Pattern | Gets worse over days or in cold weather | Can be sudden or intermittent |
Simple tests to tell them apart
- Headlight test. Turn on the headlights and try to start. If they dim a lot or go out, the battery is likely weak. If they stay bright and the car only clicks, suspect the starter or its connection.
- Voltage check. A multimeter reading around 12.6 volts at rest suggests a good charge, while readings around 12.0 or below suggest the battery is low. See the battery troubleshooting guide for testing steps.
- Jump-start or charge. If the car starts normally with a jump or after charging, the battery (or charging system) is the likelier problem.
- Check connections. Corroded or loose cables can mimic either problem.
A parts store or shop can test the battery, starter and alternator, often quickly. This is the most reliable route if the results are unclear.
Will a bad starter drain the battery?
It can. A failing starter or starter circuit may draw excess current while trying to crank, which can run a battery down faster, and repeated attempts make this worse. A starter that is stuck on or a shorted circuit can also drain a battery. If a new battery keeps going flat and the starter seems questionable, have both checked.
Can you jump-start a car with a bad starter?
Jump-starting supplies more power to the starter, so it will only help if the real problem is low battery power. If the starter has failed, the car will usually still not crank, even with good jumper cables and a strong donor car. Avoid repeated attempts, which can overheat the starter. Some people report that tapping a failing starter helps temporarily, but this is not a fix and may not be advisable on every vehicle.
Don’t forget the alternator
If the battery keeps dying and the starter seems fine, the alternator may not be recharging it. Clues include a battery warning light, dimming lights while driving, or the car dying shortly after a jump. If the battery and starter both seem healthy but the car still will not start, see these other reasons the car may not start even when the battery looks fine.