How to Test if a Car Battery is Good or Bad?
2 Answers
Use a battery tester or multimeter to measure the battery voltage. Under normal conditions, the no-load voltage of the battery should be around 13 volts, the load voltage should not be lower than 12 volts, and the starting voltage should not be lower than 9.5 volts. Check if there is obvious swelling or bulging on both sides of the battery and if there are white or green powdery substances around the battery terminals. If present, it indicates a problem with the battery performance. Here are detailed explanations of related issues: 1. If white or bluish-green powdery crystals are found on the battery electrodes, promptly clean the electrodes using a wire brush and a sodium bicarbonate solution to ensure good contact between the electrodes and cables. 2. Check if the battery is securely fixed on the battery tray. If it is loose, tighten the mounting bolts, as excessive shaking can shorten the battery's lifespan. 3. Regularly check if the electrolyte level in the battery has decreased. If necessary, add distilled water, but do not overfill. The normal liquid level should reach the bottom of the filling hole. 4. Check if the battery cables are tightly connected to the electrodes. Loose connections can prevent the car from starting. 5. Carefully inspect the battery casing. If there are cracks, replace the battery immediately to prevent leakage of corrosive electrolyte.
I've been driving for over a decade, and testing car batteries is quite simple. Using a multimeter to measure voltage is the most straightforward method. A voltage above 12.6 volts before starting indicates good health; below 12.4 volts suggests insufficient charge, possibly a sign of a bad battery. It's best to measure when the engine is cool for more accurate results. After charging, retest to see if the voltage remains stable—if not, it indicates internal issues. Additionally, inspect the battery's exterior; if the electrolyte level is too low or the terminals are severely corroded, it also means the battery is failing. I've encountered this before—the voltage dropped quickly, making the car hard to start, and replacing the battery promptly saved a lot of trouble. Regular checks are key; batteries typically last three to five years, and cold starts in winter often cause issues, so frequent testing helps prevent surprises. Safety first—don't risk breaking down on night drives. Just keep a simple meter at home for backup.
