Why does the battery still not show fully charged after 12 hours of charging?
2 Answers
The reasons why the battery still does not show fully charged after 12 hours of charging include insufficient charging voltage and battery aging. Insufficient charging voltage: If it is a 12v car battery, the voltage during charging should be around 13.8v. Once it falls below this voltage, the battery will be difficult to fully charge. Battery aging: When the car battery's mileage exceeds 50,000 kilometers and there is a phenomenon where it does not fully charge even after a long time, it indicates that the battery has aged and needs to be replaced with a new one in time. When replacing the battery, it is important to choose a battery of the same model; otherwise, it will not function properly. Additionally, during the battery replacement process, pay attention to the connection sequence of the positive and negative terminals.
If the battery still doesn't show full charge after 12 hours of charging, I suspect several possible issues. The charger itself might be faulty, such as internal circuit failure or unstable voltage, resulting in low charging efficiency. Alternatively, the battery could be severely aged with problems like excessive internal resistance or sulfation of plates, preventing it from absorbing power. Also, check if the connecting wires are loose, oxidized, or rusted, as poor contact can interrupt current transmission. Additionally, low ambient temperature affects charging speed, often requiring longer charging times in winter. If using a smart charger, incorrect settings like too low current will naturally extend charging time. It's advisable to first measure the battery voltage and charger output with a multimeter—if the voltage is below 12.6 volts, it may not be fully charged. Don't delay in addressing such issues; promptly replace the charger or seek professional inspection to avoid battery damage and subsequent vehicle use problems.
