How to Determine the Quality of a Car Battery?
3 Answers
Methods to determine the quality of a car battery: 1. Inspect the appearance for any deformation, leakage, or burn marks, and check for oxide seepage at screw connections; 2. Conduct a load test—if the battery shows no visible abnormalities but discharges significantly faster than a normal unit under a certain load and fails to restore normal backup time after charging, it indicates battery aging; 3. Measure the terminal voltage of each battery in the pack—if one or more batteries show terminal voltages significantly higher or lower than the nominal voltage, it suggests battery aging; 4. Check the charging voltage of each battery in the pack—if one or more batteries exhibit charging voltages higher or lower than others, it confirms battery aging.
In my ten years of repairing cars, I've seen too many car owners whose batteries suddenly fail. The most reliable method is to use a battery tester to check the starting voltage. If the voltage drops below 10V during a cold start, the battery is basically done for. Usually, pay attention to signs like dimming headlights or delayed starts. Recently, I tested a neighbor's battery—it looked fine on the surface, but the test showed only 23% lifespan left. The hot weather now is manageable, but you must check the battery before winter, especially for old batteries over three years old. Cold winter mornings are the most likely times for failure to start. More professional equipment can also measure internal resistance; if it exceeds 10 milliohms, it's time for a replacement.
I just replaced my car battery last month and want to share some practical tips. Many modern vehicles have battery warning lights on the dashboard, but by the time it lights up, it's often too late. Here's a simple test: After turning off the engine, keep the headlights on for 15 minutes then try starting - if it starts easily, your battery is still good. If you have a multimeter, be cautious when the resting voltage (cold engine) drops below 12.4V. In my case, the engine struggled to crank, taking about two seconds of clicking before starting. An experienced driver taught me to check the battery's inspection window - green means good, black means replacement needed. Also, frequent short trips can drain your battery, so it's best to take at least one 30-minute drive each month to fully recharge it.
