Quick Answer
Over-discharging a lithium battery is characterized by visible signs such as a swollen or bloated case, a bulging or deformed shape, and visible thermal damage. These physical changes can lead to a complete loss of capacity, rendering the battery unusable.
Signs of Over-Discharging
Over-discharging a lithium battery can be identified by observing its physical condition after discharging. Signs may include a swollen or bloated case, a bulging or deformed shape, and visible thermal damage such as blisters or cracks on the surface. These physical changes occur when the battery’s internal electrolyte is pushed out of the cell and into the surrounding space, causing it to swell.
Effects on Capacity
Lithium-ion batteries have a nominal capacity of 3.7 volts per cell, but they can be safely discharged to as low as 2.5 volts per cell. However, going below 2.5 volts can cause permanent damage to the battery’s internal structure. To avoid over-discharging, it’s essential to use a battery monitor or a voltage-controlled charging system to prevent the battery voltage from dropping below the safe threshold.
Prevention and Maintenance
To prevent over-discharging, it’s crucial to maintain a healthy State of Charge (SoC) between 20% and 80%. Regularly checking the battery’s SoC and voltage can help identify potential issues before they become severe. Additionally, storing lithium-ion batteries away from extreme temperatures and moisture can help prolong their lifespan. It’s also essential to follow proper charging and discharging procedures to avoid causing unnecessary stress on the battery.
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