What does UPS battery deep discharge mean?
Deep discharge generally refers to the discharge of approximately 80% of the rated capacity of a battery. UPSpower batteries will inevitably have some active substances sinking after a period of use. If the active substances are not activated in time, it will inevitably have some impact on the capacity of the battery. Therefore, it is best to conduct deep discharge of electric vehicle batteries every few months, which is beneficial for extending the battery life. But avoid excessive discharge, otherwise it will cause damage to the battery.
During the discharge process of UPS power batteries, lead dioxide and sponge lead form small crystal blocks of lead sulfate in a chemical reaction. After excessive discharge, lead sulfate will form many larger crystal blocks. When the crystal blocks are unevenly distributed, the electrode plate will warp irreversibly, while increasing the internal resistance of the electrode plate. During charging, the lead sulfate crystal blocks are difficult to restore, which hinders the charging process.
What are the reasons for excessive deep discharge of UPS power batteries?
Most UPS power supplies have the highest efficiency between 50% and 100% load, and their efficiency drops sharply when the load is below 50%. Therefore, it is not cost-effective for UPS to operate at excessively light loads from an economic perspective. In addition, some users always believe that the lighter the load, the higher the reliability of machine operation and the lower the failure rate. However, this concept is not comprehensive because light load can reduce the probability of damage to the final power tube, but it is extremely harmful to the battery. Due to excessive light load operation, if the UPS power supply battery does not have a deep discharge protection system after a power outage, it may cause excessive deep discharge of the battery, resulting in permanent damage to the battery.
(1) Long term low current discharge. As we all know, the capacity used by UPS power batteries is closely related to the discharge current. The smaller the discharge current, the more capacity is actually discharged. Generally speaking, the discharge capacity of a battery must be controlled within 80% of its rated capacity. That is to say, when the battery discharges 80% of its rated capacity, it is not allowed to continue discharging. If the discharge continues, it will cause deep discharge of the UPS battery. If remedial measures are not taken in a timely manner, it may cause permanent damage to the battery.
(2) Long term frequent discharge. Some units and regions may experience frequent discharge of UPS power batteries due to frequent power outages. If there is not enough time to charge the battery after it has been discharged, and it is discharged immediately the second time, it may cause deep discharge of the battery.
UPS has a minimum voltage protection value for the battery, but the relationship between the terminal voltage of the battery and the discharge current is closely related. When the discharge current is small, the terminal voltage is high, and the actual capacity released when reaching the minimum protection value is greater. Therefore, UPS operating under light load should try to avoid the phenomenon of discharging to the lowest protection value before shutting down. Long delay UPS should appropriately increase the discharge lower limit voltage protection value.