Lead Acid battery failure is never an instantaneous event, this failure is actually a long-term cumulative degradation process, mainly driven by three core factors: plate sulfation, grid corrosion, and electrolyte drying.
If there is a lack of necessary maintenance and monitoring, coupled with improper charging strategies, high temperature environment or excessive deep discharge, these hidden electrochemical changes will quietly accumulate until the battery suddenly and completely strikes at a critical moment.
This is the most common cause. When the battery is discharged, lead sulfate is formed on the plates. In theory, the charging process should be able to convert it back, but the reality is that over time, these deposits harden and crystallize over time. The crystalline layer is like a layer of “insulating shell”, which tightly wraps the polar plate and directly hinders the chemical reaction of the active material. Simply put, charging cannot be charged and discharging cannot be discharged. This is a physical barrier.
The lead alloy grid inside the battery is not only the carrier of the active material, but also the conductive network of power transmission. As battery life advances, oxidation and corrosion are inevitable. When the corrosion goes deep, the conductive path will be blocked and even lead to structural collapse. In many cases, the cliff-like decline in battery performance often starts from this structural damage.
Lead-acid batteries rely on an electrolyte for ion transport. Once the water is evaporated and lost due to gas evolution, the acid concentration will increase abnormally, and the part of the polar plate exposed to the air will be rapidly damaged, directly interrupting the electrochemical reaction chain.
Mechanical failure is the root of the disease, but operation and maintenance habits and the environment are often catalysts.
Charging protocol deviation: The charging strategy directly determines the life of the battery. Long-term undercharging will lead to ineffective conversion of lead sulfate, thus accelerating sulfidation; while overcharging will cause internal overheating and serious gas evolution, which will directly lead to drying up of the electrolyte and aggravation of corrosion.
The ambient temperature is too high: lead-acid batteries are extremely sensitive to temperature. High temperatures can cause internal chemical reactions to enter an “overspeed state”. According to the data, every time the temperature deviates from the standard value by a few degrees, the battery life expectancy will be reduced by half, which is a very cruel reality.
Deep discharge cycle: Frequent deep discharge will cause great pressure on the active material. The plates are prone to fall off during repeated contraction and expansion, and this deep damage is usually irreversible.
All of the above physical damage will eventually point to a core indicator: increased internal resistance. When lead sulfate crystallizes and corrosives block the channel, it becomes extremely difficult for current to pass.
This also directly affects the state of health (SOH) of the battery. SOH measures the current actual capacity of the battery compared to the initial capacity. When SOH falls below the critical point, even if the battery case looks intact, its structure can no longer support the design load.
Author: Kevin
I am a Senior Engineer at Gerchamp’s BMS R&D Department with over 12 years of industry experience. I specialize in leading the architecture design and core algorithm development for our advanced Battery Management Systems.
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