Method for charging nickel-hydrogen, nickel-cadmium batteries

Abstract

The invention discloses a charging method for nickel-hydrogen and nickel-cadmium cells, wherein the charging process of a cell is divided into N sections, threshold valves and limit values of which are determined; when the cell is charged, if the negative value increasing of the voltage occurs, whether the cell is normally charged is judged; if the charging is abnormal, the charging process is directly jumped to the N section and enters the trickle charge state; when the cell voltage corresponding to the limit value of any section is lower than the threshold value of the section, the charging process is directly jumped to the N section and enters the trickle charge state. The method and the device adopting the invention can quickly enter the charging protection state when the cells are abnormal, thereby achieving an aim of safe charging.

Description

technical field [0001] The invention relates to fast charging technology, in particular to a charging method for nickel-metal hydride and nickel-cadmium batteries. Background technique [0002] Fast charging of Ni-MH and Ni-Cd rechargeable batteries will involve a series of issues such as charging time, whether it is overcharged, temperature, battery life, etc. [0003] like Picture 1-1 , Figure 1-2 As shown, at room temperature, when the nickel-hydrogen and nickel-cadmium batteries are fully charged, that is, when the battery capacity is charged to 100% as shown in the figure, the voltage reaches more than 1.4v, and the battery voltage begins to drop after continuing to charge after fully charged , the temperature of the battery rises rapidly. High temperature will shorten the life of the battery. In order to ensure that the battery is fully charged without overcharging and causing high temperature of the battery, methods such as timing control or voltage control are ge...

AI Technical Summary

Problems solved by technology

The disadvantage of this control method is that the maximum voltage of the fully charged battery varies with the ambient temperature and charging rate, and the maximum charging voltage of each single battery in the battery pack is also different, so this method cannot be used to judge the battery very accurately. Is it fully charged

The disadvantages of this control method are: Picture 1-1 As shown in the charging voltage curve of a single-cell Ni-MH or Ni-Cd battery at a room temperature of 25°C, after a negative increase in the battery voltage, the battery has been overcharged, so the temperature of the battery is relatively high

In particular, after the Ni-MH battery is fully charged, it takes a long time for the battery voltage to show a negative increase, and the overcharge is serious.

[0008] The above method cannot detect abnormal charging during the charging process and take protective measures, such as timing control. When the ambient temperature is very high and the charging is abnormal, the voltage rises slowly, or even negative growth occurs, the fast charging state is maintained until the set time, that is, Stop charging, and the set time is the time required for the battery to be fully charged during normal charging, so that the battery stops charging even if it is not fully charged; voltage control, when it reaches the highest voltage or appears Negative voltage, stop charging, When the ambient temperature is very high and the charging is abnormal and the voltage rises slowly, maintain fast charging. In this way, due to the slow voltage rise, the time to reach the highest voltage or overcharge is prolonged, that is, the time for the internal temperature of the battery to accumulate is prolonged, and the internal temperature of the battery is further reduced. If the temperature is too high, it will seriously shorten the battery life, or even destroy the battery

Images