What to Do When the Battery is Undercharged and Won't Charge?

[LaEmery]

Check if the fuse has poor contact and reconnect it. Replace the wiring. If the battery has been used for a long time, the electrolyte may decrease, and it needs to be refilled. Replace the battery.

[KalebAnn]

A while ago, my car battery was undercharged and wouldn't take a charge, which really worried me. I was using a regular charger, but it just wouldn't charge. Later, I learned that the battery was excessively discharged with too low voltage. First, I checked the battery terminals—no looseness or corrosion—then borrowed a friend's smart charger with activation function, but even after charging overnight, there was no response. As a last resort, I drove to a repair shop where the mechanic tested it and said the internal resistance was too high—the battery had aged over five years and needed replacement. They advised against forcing a charge in such cases to avoid risks like battery swelling or short-circuit fires. Now, I use a cigarette lighter voltage monitor to regularly check and prevent undercharging issues.