What are the consequences of water entering a car battery?
3 Answers
Water ingress can cause short circuits and other phenomena in the battery. Here are the relevant details: 1. Distilled Water: If a car battery is soaked in water and not treated promptly, it may become unusable. Although the battery contains water, it is different from regular water. The water inside the battery is typically distilled or high-purity water, with very low conductivity, making it essentially non-conductive. 2. Battery Discharge: This can lead to sulfation of the battery. If severe discharge occurs, it may even render the battery irreparable. Battery discharge refers to deep discharge, where the voltage drops below 10.50V, causing sulfuric acid to react with the lead plates to form lead sulfate. If not recharged promptly, the lead sulfate can crystallize. Over time, these crystals may not decompose even after recharging, a condition known as battery sulfation.
I once experienced a car battery getting flooded. After a rain, I didn't pay attention to the parking spot, and the accumulated water in the garage submerged the battery, causing the car to fail to start the next day. The consequences were quite alarming: internal short-circuiting in the battery, smoke, and sizzling sounds; acid leakage corroded the surrounding metal parts, costing over a thousand dollars to repair; and even more dangerously, the accumulation of hydrogen and oxygen could have caused an explosion with just a tiny spark—I was terrified at the time. On top of that, the battery's capacity rapidly declined, unable to sustain the air conditioning, and it completely died within a week. Later, I learned that when a battery gets flooded, you shouldn't delay—immediately disconnect the power, dry it with a towel, and then take it to a professional shop for inspection or replacement. For daily parking, avoid low-lying areas, and before the rainy season, get the battery checked for sealing to save a lot of trouble.
A flooded battery is no small matter. As an auto repair technician, I've seen countless cases like this. Water infiltration can cause electrode short circuits, accelerate self-discharge, drain the battery overnight, and leave your car unable to start. Severe corrosion leads to oxidation and rusting of internal lead plates, ultimately causing complete failure. It may also trigger leakage and bubbling, with gas accumulation posing explosion risks under high temperatures. Immediately turn off the engine and disconnect power - don't attempt to restart. Then take it to a shop for disassembly, cleaning, or replacement. Maintain a dry engine compartment, regularly clean battery covers, and avoid direct water spray during car washes. These habits can multiply your battery's lifespan.
