What does it mean when a car battery test shows plate damage?
3 Answers
It indicates that the plates of the car battery are damaged. Here is relevant information: 1. Introduction: A car battery is a type of battery, also known as a storage battery, which works by converting chemical energy into electrical energy. The commonly referred car battery is a lead-acid battery, which mainly uses lead and its oxides as electrodes and sulfuric acid solution as the electrolyte. 2. Classification: Conventional batteries, dry-charged batteries, and maintenance-free batteries. 3. Principle: A lead plate filled with sponge-like lead serves as the negative electrode, a lead plate filled with lead dioxide serves as the positive electrode, and 22-28% dilute sulfuric acid is used as the electrolyte. During charging, electrical energy is converted into chemical energy, and during discharging, chemical energy is converted back into electrical energy.
Last time my car suddenly wouldn't start, and the diagnosis said the plates were damaged. Essentially, those metal plates inside the battery were ruined—they're responsible for generating the electrochemical reaction. Just like when a person's heart fails, once the plates go bad, the entire battery is done for. The most obvious signs are unstable voltage causing the headlights to flicker and the car making a clicking sound when trying to start but failing to ignite. This issue is usually caused by long-term neglect, like leaving the headlights on, leading to over-discharge, or the battery aging after three to five years without replacement. There's no way to repair it—the whole battery needs to be replaced. A domestic replacement at a roadside shop for around 400 yuan will suffice, but remember to have the technician perform a charging match after installation. Usually, make sure to confirm the power is off after parking to avoid leaving the battery undercharged for extended periods.
In automotive repair jargon, damaged plates mean the core structure inside the battery is completely ruined. Those dozen or so lead-calcium alloy layers are the critical components for storing electricity—once they crack, corrode, or become sulfated, it's game over. The two most common symptoms I encounter are: difficulty cold-starting, with dashboard voltage dropping below 10V, or overnight charging failing to replenish the battery. Nowadays, many car owners install high-power audio systems or retrofit LED light strips, which overload the current and severely damage the plates. During diagnostics, professional equipment performs deep discharge tests—if internal resistance exceeds 5 milliohms or capacity degrades by 30%, it's an immediate death sentence. Such a dead battery must be fully replaced; patch-up repairs are just money down the drain. When replacing, opt for AGM-technology batteries for better durability.
