Why is the car battery smoking?
2 Answers
During driving, if the battery smokes and emits a foul odor, the main reasons are likely electrolyte leakage or depletion. Below is relevant information about car batteries: Introduction: A car battery, also known as a storage battery, is primarily made of lead and its oxides, with the electrolyte being a sulfuric acid solution. Its working principle involves converting chemical energy into electrical energy. Classification: There are three types: conventional batteries, dry-charged batteries, and maintenance-free batteries. Conventional batteries have plates composed of lead and lead oxides, with the electrolyte being an aqueous solution of sulfuric acid. The main feature of dry-charged batteries is that the negative plate has a high capacity for storing electricity. In a completely dry state, it can retain the stored charge for up to two years. When in use, you only need to add the electrolyte and wait 20-30 minutes before it can be used. Maintenance-free batteries, due to their structural advantages, consume very little electrolyte and generally do not require the addition of distilled water during their service life.
I've worked in an auto repair shop for over a decade and have seen many cases of car battery smoking. The most common cause is a faulty charging system, such as a broken alternator voltage regulator that overcharges the battery, causing internal heating and steam emission. It could also be due to battery aging, internal short circuits causing electrolyte decomposition producing smoke, or loose terminal connections leading to poor contact and heat buildup. If you notice smoke, immediately pull over safely, turn off the engine, and use insulated gloves and a wrench to disconnect the negative battery terminal to avoid sparks. Do not pour water directly on it as acid may splash and cause injury or worsen corrosion. After the vehicle cools down, inspect the battery for cracks or leaks, then have a professional shop test the charging circuit and battery health. Regular maintenance includes cleaning battery terminals and applying anti-corrosion grease every six months, plus periodic voltage checks to ensure stability.
