What are the methods to distinguish between good and bad batteries?
4 Answers
Methods to distinguish between good and bad batteries are: 1. Inspect the appearance: Check if the battery casing is bulging, leaking, has broken separators, or corroded terminals. If these signs are present, it indicates the battery is dead; 2. Test the voltage: After charging for two hours, measure the voltage of individual battery cells every 20 minutes. If the voltage is below 13, it indicates a problem. During discharge, test every 10 minutes in three intervals. If the discharge time is faster than other batteries and the voltage drops below 10V, the battery is faulty; 3. Check for water loss and blackening: After charging the battery for 36 hours, if the charger's red light remains on, it indicates severe water loss. Open the battery's top cover to reveal six round holes. Check the color of the electrolyte in each hole. If it appears black, it means the lead powder from the plates has fallen off, indicating the battery is dead.
Distinguishing between good and bad car batteries relies on experience and observation. As a driver, I have a simple trick: after parking and turning off the engine, turn on the headlights or honk the horn—if the lights are bright and the sound is crisp, the battery is healthy; if dim or sluggish, it might be aging. Another method is during vehicle startup: a good battery makes the engine roar immediately when turning the key, while a bad one may delay or produce clicking sounds. Don’t forget to inspect the battery itself: pop the hood and check for leaks, swelling, or corroded terminals; white crust indicates poor connections. For maintenance, I regularly clean the terminals with a brush or anti-corrosion spray to prevent rust. Voltage testing is also useful: use a multimeter to measure the open-circuit voltage—12.6 volts or higher is normal; below 11 volts is risky. Batteries typically need replacement every two to three years, especially before cold weather, to avoid sudden failures. These small habits save me from unnecessary trouble.
I have some interest in car DIY, and evaluating the battery isn't difficult. A good battery has low internal resistance and stable output, which can be seen through a tester: the open-circuit voltage should be between 12.4-12.8 volts, and not drop below 10 volts during startup—lower readings indicate performance degradation. Physical condition is also crucial: clean terminals without corrosion, and no cracks or bulges on the casing. I usually use an inexpensive tester; if the voltage drops slowly under load (like turning on the AC), it's a strong battery. A crisp and short startup sound is also a good sign. Common causes of battery aging include over-discharge, so I turn off all electronics before parking. A related reminder: a bad battery increases the alternator's workload, so replacing it early saves repair costs. Choose reliable brands and don't skimp on quality. In short, DIY testing is quite convenient.
After driving for most of my life, I can intuitively tell if a battery is good or bad. If the engine starts smoothly without hesitation, it's good; if it takes a long time to start, there's definitely a problem. The dashboard helps a lot: if the voltage needle is too low or the warning light is on, don't hesitate to get it checked. In daily use, turn on the headlights and observe—steady brightness means the battery is fine, while flickering may indicate high internal resistance. Check the battery surface: if there are signs of leakage or severe corrosion on the terminals, replace it immediately. I make it a habit to check before cold weather sets in, as freezing temperatures can prevent startup. Batteries typically last two to three years, so replace them when due. Simple maintenance like cleaning the terminals to prevent oxidation helps. This method has saved me from trouble many times.
