What causes a battery to overheat and fail to charge fully?

[AliviaFitz]

If a battery consistently fails to charge fully and becomes hot, it may be due to battery aging or reaching the end of its service life. Batteries have a limited lifespan, typically ranging from 2 to 3 years. If charging becomes impossible, the battery's lifespan should be considered. Solutions for a battery that won't charge fully: If the battery has reached the end of its life, it needs to be replaced; if a fuse is blown, visit a 4S shop or repair shop to have a professional replace the fuse; poor contact between the fuse holder and fuse socket requires professional attention. If there's poor contact with the power source, unplug the charger and reconnect it to ensure proper contact. Battery usage precautions: Avoid using vehicle electrical devices, such as listening to the radio or watching videos, when the engine is off; if the vehicle is parked for an extended period, disconnect the battery, as even when the vehicle is locked remotely, the electrical system enters a dormant state but still consumes a small amount of current; frequent short-distance driving can prevent the battery from charging fully, significantly shortening its lifespan. Regularly drive the vehicle on highways or use an external charging device to maintain the battery.

[DelLuke]

I've dealt with similar car battery issues before - overheating and failure to fully charge are usually signs of internal failure. After several years of use, batteries tend to age, and sulfation of the plates can impede charging, leading to internal short circuits that generate heat, resulting in excessive current and incomplete charging. The charger might also be incompatible, such as having an output voltage that's too high, which can overheat the battery and prevent it from completing the charging cycle. I recommend first checking the battery's lifespan by feeling its surface for excessive heat, then using a multimeter to measure the terminal voltage - it should normally be around 12.6V. If the temperature spikes during charging, stop using it immediately to avoid explosion and promptly visit a repair shop to replace the battery or check the charger. In daily use, avoid deep discharging the battery, and remember to turn off headlights after parking to extend its lifespan - this can significantly reduce such problems.

[VanAdeline]

As someone who loves tinkering with cars, a hot battery that won't charge fully is really frustrating. Most likely, the battery itself is dead, with issues like increased internal resistance or dried-up electrolyte, causing current to get stuck and generate heat during charging without storing energy. Incorrect charger settings are another pitfall—excessive output voltage can lead to overload. For a simple DIY check: first, inspect the battery terminals for oxidation or looseness, clean off any rust and tighten if loose; then charge for five minutes and feel the temperature change—stop if it gets too hot. If it's an old battery that still lacks power after an hour of charging, it's probably time to replace it—don't risk driving to avoid stalling. To prevent recurrence, avoid using the battery for high-power devices and ensure proper ventilation during charging.

[JudahDella]

I'm a new driver, and it's really annoying when the battery gets hot and won't charge fully. From what I understand, there are two common causes: First, the battery is too old, and the increased internal resistance makes it hard for the current to flow, like traffic congestion—charging heats it up but leaves it half-dead. Second, the charger might be faulty, such as having the voltage set too high or being the wrong model, which overheats the battery and prevents a full charge. A simple step is to stop charging and check if the battery casing is hot to the touch. If it is, there's a high risk of internal short-circuiting, and it's time for a replacement. Beginners shouldn't force it; it's safer to have a professional shop test it to avoid accidents. Usually, remember to turn off the engine and electrical devices when parking to prevent the battery from draining and reduce trouble.