How to Determine if a Car Battery is Good or Bad?

[RyanDella]

Methods to determine the condition of a car battery are as follows: 1. Check if the battery is swollen: When a battery swells, it is mostly due to the internal pressure of the battery increasing under high temperatures, causing the pressure relief valve to open automatically. Once the pressure relief valve opens, it accelerates the loss of water from the battery. Excessive water loss leads to a decrease in the battery's activity, making it prone to issues such as heating of the casing, bulging, and deformation during charging, commonly known as battery swelling. 2. Observe the color of the battery surface: Check around the battery terminals for any white or green powdery substances. High-quality or new batteries generally do not have these oxides. Their presence indicates that the battery's performance is starting to deteriorate.

[Herb]

I remember one winter morning when the car sounded particularly labored during startup, almost like it was gasping for air. At the time, I guessed the battery might be failing. Later, I learned from a car enthusiast group that the simplest method is to use a voltmeter to check – during normal startup, it should read around 12 volts. If it drops below 10 volts, the battery might be on its last legs. Another indicator is the ignition performance; if every start is sluggish, don’t wait too long – replace the battery promptly. Otherwise, the car might stall midway, and that would be truly awkward. I’ve also tried checking the battery terminals for corrosion or looseness. If they’re rusty, cleaning them with a baking soda solution can improve electrical contact. In short, the condition of your battery is a safety issue – don’t skimp on it. Especially before long trips, always test it thoroughly.

[VonBryce]

I just bought a car not long ago, and I'm most afraid of battery issues. For me, the way to judge is quite straightforward: observe the lights when starting the car. If the headlights dim noticeably or flicker when starting, it indicates the battery is low. Another red flag is if the car starts very slowly after being left unused for a few days. I usually pop the hood to check if the battery casing has any bulges or cracks, as these could mean leaks. Also, listen to the sound when starting—normally it's a smooth roar, but if it's intermittent like a cough, it might mean insufficient power. I recommend mentioning it during regular maintenance; auto repair shops can check it for free. Don't wait until you're stranded on the road.

[LaAmelia]

I usually enjoy tinkering with cars. To check battery health, I often use a load tester, which can simulate starting loads and measure whether the remaining capacity is sufficient. A normal reading should be above 80%, and if it drops below 50%, it's time for a replacement. Also, inspect the battery terminals—if there's severe green corrosion, it indicates internal damage affecting conductivity. Typically, car batteries last 3 to 5 years, so older ones require more attention to terminal voltage checks. For a simpler method, just watch the battery warning light on the dashboard while driving—if it lights up, address the issue promptly.