Can a Swollen Car Battery Still Be Used?

[McCarlos]

Car battery swelling indicates that the internal plates have deformed, posing significant safety hazards. It should be promptly replaced with a new battery or sent back to the manufacturer for repair. Continued use may lead to combustion, explosion, or the release of toxic gases. There are several reasons for car battery swelling: one is long-term overcharging, which causes the battery grid to fracture and deform or the active material to expand, resulting in swelling; another is blocked battery vents combined with overcharging, preventing the release of gas inside the battery and increasing internal pressure—this situation is extremely dangerous and may lead to an explosion; a third reason is a cracked battery casing, allowing air to enter the battery. The moisture in the air reacts and decomposes into oxygen and hydrogen, causing the battery to swell.

[Donovan]

If the battery is already swollen, it really can't be used anymore! Last time my car was like this, I found the hood slightly lifted when starting it in the morning. I rushed to the shop for an inspection, and the boss said it was an internal short circuit with acid leaking out, which is extremely dangerous. It could suddenly explode on hot days or bumpy roads, and if the battery casing breaks, strong acid could spray everywhere. I initially thought about saving money and continuing to use it, but after hearing that, I was terrified. I ended up spending over 300 yuan to replace it with a new battery. In fact, swelling is a clear sign that the battery is completely dead—even if it can still start the car, it must be replaced. Never try to save money by taking risks.

[SanRhett]

I've encountered battery swelling twice, both due to aging after three or four years of use. When you see bulging on the sides or top, it usually indicates uncontrolled internal chemical reactions. At this point, the battery could leak electrolyte at any moment—mild cases corrode the bracket and surrounding metal, while severe cases may cause the battery to burst and injure people. Last time, a neighbor's kid poked a swollen battery out of curiosity, and the splashed acid burned a hole in their pants. So if you notice any deformation, immediately disconnect the battery cables, remove it, and take it to a recycling center for safe disposal. A new battery now costs between 300 to 500, which is still cheaper than repairing car damage.

[DelDeclan]

Swollen batteries must be replaced! It's essentially a chemical reaction runaway issue—the lead plates and electrolyte inside lose control, producing excessive gas that deforms the casing. This condition is highly unstable; even vehicle vibrations could crack the shell. Leaking strong acid rapidly corrodes chassis components, like mounting brackets rusting through in just 2-3 days. Not to mention the risk of gas accumulation during charging causing the battery to explode like a balloon. I learned this the hard way by stubbornly using a swollen battery—it leaked and ruined all the wiring in the engine bay, costing ¥800 just for electrical repairs. Professional workshops won't even accept such hazardous waste batteries. Safety comes first.