Why can't the battery be fully charged?
3 Answers
The reasons why the battery cannot be fully charged: Battery lifespan expired: If the electric vehicle cannot be charged, the first consideration is the battery lifespan issue. Generally, the battery lifespan cycle is 2-3 years, and the main factors determining lifespan are related to the user's usage habits. Perform daily proper battery maintenance. Fuse blown: If the internal fuse of the battery is blown, the battery will have no power. Professional repair is required at a maintenance shop. Poor contact: When there is poor contact between the fuse tube and fuse holder, the electric vehicle battery may also fail to charge or not charge fully.
I found that there are usually several types of issues when the battery cannot be fully charged. The most common problem is a fault in the vehicle's charging system, such as a loose or damaged alternator belt, which prevents the alternator from keeping up with the required speed. A faulty voltage regulator can cause the charging voltage to be too high or too low. Daily usage habits are also crucial—if you frequently drive short distances in the city, the alternator simply doesn’t have enough time to fully charge the battery. Problems with the battery itself, such as sulfation—where white crystals form on the electrode surfaces—or insufficient electrolyte levels that don’t cover the plates, can also prevent full charging. Additionally, installing too many electrical accessories leading to power leakage or aging wiring with poor connections can affect charging efficiency. It’s recommended to visit a professional auto repair shop for a comprehensive charging system inspection rather than blindly replacing the battery and wasting money.
A car battery is like a bucket - when the bucket itself ages, no matter how much you fill it, it won't hold properly. I've encountered several classic cases: after 2-3 years of use, the active material on the internal plates severely detaches, causing a sharp decline in charge storage capacity; the electrolyte becomes cloudy with bubbles, and precipitated impurities create internal short circuits. Even when the charger shows full, the actual capacity may only be 70%. High temperatures accelerate internal evaporation, exposing plates to air oxidation when water levels drop. Here's a lesser-known fact: charging efficiency drops by nearly 30% in cold conditions. For accurate diagnosis, use a voltmeter to measure pre-start voltage when cold - readings below 12.4V should raise concerns.
