What are the methods for testing a car battery?
2 Answers
Currently, most car batteries on the market are tested using a battery tester to measure the battery's voltage. Typically, the no-load voltage of a battery is around 13 volts, and the full-load voltage should not be less than 12 volts. Additionally, observe whether there is obvious swelling or bulging on both sides of the battery. If white or green powdery substances appear around the battery terminals, it indicates a performance issue with the battery. To determine if the electrolyte has deteriorated or lost water, charge the battery for 3 to 6 hours, then touch the side of each battery cell's casing by hand. If the battery feels hot to the touch, it means that cell has failed. Another method is to open the cover on top of the battery, where you can clearly see six round holes beneath it. Carefully inspect the color of the electrolyte in each hole. If the electrolyte has turned black, it indicates that the lead powder from the plates has fallen off, meaning that cell has failed.
As a seasoned mechanic with decades of experience, I recommend starting battery checks with a voltage test. Simply use a multimeter to measure - a healthy battery should read around 12.6 volts. If it drops below 12 volts, the battery may be aging and require charging or replacement. Next, open the battery caps to check electrolyte levels, topping up with distilled water to the standard line if low. Never use tap water as it can corrode the internals. Load testing is equally important - use professional equipment to simulate the starting process and observe whether voltage drops below 10 volts, which helps identify hidden issues. Terminals and connectors require regular inspection too; if corrosion appears, remove them and clean with a small brush and baking soda solution to ensure secure contact. Neglecting these can lead to roadside breakdowns - I've witnessed countless stranded vehicles. I recommend checking every six months, especially during cold weather when battery performance declines faster. Always remember to turn off all electronics after parking to reduce power leakage risks.
