Why Your Car Isn't Starting
Every wonder why your car won’t start? One of the reasons may be a weak or dead battery. If you have a battery tester that can measure cranking amps, use it to see if the battery is weak. If you can’t test the battery, try jump-starting. If the car starts right away, your problem is most likely a dead battery. Charge the battery and clean the terminals and cable connectors to ensure good contact. If your car does not start by jump-starting, you may have a problem with your starter, alternator or another component of the electrical system. Be sure to read and follow all safety and handling instructions on the battery and this website.
Common Causes of Car Battery Failure
Heat is the No. 1 cause of battery failure. Heat accelerates grid corrosion and grid growth in the positive plate. As heat corrodes the positive grid, the battery loses capacity and starting power, which weakens its ability to start an engine – particularly in colder weather.
Vibration can damage and separate internal components, which ultimately leads to reduced starting performance or even battery failure.
Deep drains/failure to recharge after drops in voltage
When a battery is discharged, the active materials produce lead sulfate crystals inside the plate that are called discharged material. If these crystals are not recharged, they eventually combine to form larger crystals. These bigger crystals are harder to dissolve and recharge, and eventually they lead to battery failure by disrupting the plate structure.
A faulty alternator
A faulty alternator will lead to an undercharged or completely discharged battery. An undercharged battery has reduced capacity and starting power. If the battery is continuously undercharged because of a weak alternator, the battery will become deeply discharged and sulfation will occur.
Other Possible Causes of Car Battery Failure
Battery application and installation
- The battery is not being used in the application for which it was designed. A common mistake, for example, is using an SLI (Starting-Lighting-Ignition) battery in a vehicle that requires a deep-cycle battery.
- The battery is not sized properly for the application.
- The vehicle has too many electrical accessories.
- The battery is not properly installed.
Service and maintenance
- The battery cables have not been cleaned and properly adjusted to fit the battery terminals.
- The vehicle’s electrical system has been repaired or altered.
- The vehicle has been in long-term storage.
Why do I keep going through batteries if I only drive my car a short distance to work every day and have no accessiories?
If your driving style is mostly short trips several times a day, you might not be giving your alternator enough time to recharge the battery after starting the car, which causes a quick voltage drop. There are several factors that affect an alternator’s ability to adequately charge a battery, including:
- How much current (amperage) from the alternator is diverted to the battery to charge
- How long the current is available (drive time)
- Battery temperature (in cold climates batteries take more time to charge)
- Battery age
If the vehicle is not driven far enough to let the alternator fully recharge the battery, use a battery charger to restore it to full capacity.