1, if the two groups of batteries have lost capacity or owe capacity, backward quality problems, when the discharge to the rectifier output protection time, not easy to be found in time maintenance personnel, this time may reserve battery capacity is low, there is a high risk In this case, this discharge method is less safe than the offline discharge method;
2, the battery discharge current between the groups is not balanced. Each group of batteries will be based on their own natural distribution system load current to discharge, behind the battery pack, internal resistance, current sharing small, and healthy battery pack, low resistance, sharing current , Resulting in certain backward cells due to the discharge current is not big enough and can not be exposed to the phenomenon that we can not discharge the purpose of quality testing;
3, due to the depth of discharge is limited, the purpose of maintaining the battery activity of the discharge test can not be achieved, the more important point is that in the practice of full capacity discharge we often find that some of the battery group in the early discharge performance, but in the late , Some backward cells began to gradually exposed.This part of the lagging monomer, where the depth of the discharge mode is not enough to be found.So we call this discharge method for online evaluation, it can only roughly assess the battery performance, or detection This battery pack can be discharged to protect the voltage for the length of time, and can not further check in addition to this time, how long it can discharge;
4. Adjust the rectifier output voltage to protect the low voltage value (such as 46V), so that all the backup battery packs directly discharge the actual load to the rectifier output voltage protection set value.Because most of the existing network system equipment battery backup power supply time is 1 ~ 4h, the discharge current is large, the voltage drop of the battery pack to the equipment supply circuit and the working threshold of the low voltage of the equipment should be considered, and the safety of the system power supply should be ensured. The online evaluation type discharge can not adjust the output voltage of the rectifier too low (such as 46V) It is difficult to grasp the discharge time of the actual load, it is difficult to accurately evaluate the battery capacity, and there are uncertainties in the battery performance test. Therefore, it is difficult to achieve the expected maintenance effect for the purpose of discharging the battery for maintaining the battery activity.
