Test your battery when you notice that your engine starts slowly or fails to start at all when you turn the key. If the battery does not need replacement, then the starter needs replacement. Many of the signs of a bad starter and a bad battery are the same.
- Watch the lights when you try to start the engine
Check the dash lights to see if they dim while you are cranking the engine. Turn the headlights on; if they are bright when the engine is off but become dim when you try to turn the car on, the starter is possibly at fault.
- Check the battery terminals and cables after trying to start the car
Put a cloth over your hand to protect it. Grasp either one of the cables leading to the positive and negative terminals; if it is hot, the starter is likely the culprit when the engine turns over slowly. Touch the battery terminals through the cloth to see if they are hot as well.
- Listen when you try to start the engine
Listen carefully when you try to start the car. Consider changing the battery if the engine turns over at a fairly normal rate but does not start, but consider troubleshooting the starter if you just hear one click or if you hear nothing at all.