If a battery is deeply discharged, that is, discharged beyond the minimum recommended charge level, several negative consequences may occur:
① Capacity loss: Deep discharge will cause permanent loss of battery capacity. This means that the battery will no longer be able to store power as it did before, thus reducing the overall range or operating time of the device or vehicle.
② Increased wear: Deep discharge accelerates the wear of the battery's internal components. For lithium-ion batteries, this causes degradation of electrode materials, resulting in reduced performance over time.
③ Risk of damage: Some batteries, especially lithium-ion batteries, may suffer irreversible damage if over-discharged. This may render the battery unusable or severely impair its ability to charge.
④ Difficulty in Charging: A deeply discharged battery may be difficult to charge when reconnected to a charger. This is because the battery voltage may drop too low for the charger to recognize, or the internal resistance may increase, resulting in reduced charging efficiency.
⑤ Overheating and safety risks: In extreme cases, attempting to charge a deeply discharged battery may cause overheating, leading to safety hazards such as thermal runaway, which may cause the battery to swell, leak, or even catch fire.
⑥ Shortened lifespan: Regular deep discharge can significantly shorten the overall lifespan of a battery. Most batteries are designed to operate within a specific charging range, and frequent deep discharges can cause the battery to exceed its optimal operating conditions.
To avoid these issues, it’s important to monitor the battery’s charge level and recharge it before it gets too low. Many devices and electric vehicles have built-in battery management systems (BMS) that help prevent deep discharge by warning or shutting down the device before the battery becomes overly discharged.