Why can’t old and new APC UPS batteries be mixed

Due to different batches,models,and internal resistance of new and old APC UPS batteries, there are differences in the charging and discharging of these UPS batteries. When used together, it can cause some batteries to overcharge or undercharge, thereby affecting the entire APC UPS battery pack. In order to ensure the normal operation of the APC UPS power system, while using the APC UPS power supply, it is also important to pay attention to the maintenance and upkeep of the UPS battery pack. Regular charging and discharging tests should be conducted on the battery pack to extend its lifespan and avoid situations of insufficient power supply during power outages.