Explanation of maintenance knowledge about Ni-MH battery

Ni-MH battery maintenance-charging Regarding the maintenance of Ni-MH batteries, take charging as an example, today I will give you an analysis. Constant current charging The constant current charger is usually a wall transformer, as the name suggests, it supplies a constant regulated current. They don't know when the battery pack is full, they charge until they disconnect. When the charger matches the battery pack, the best charging rate is 0.1°C or 1/10 of the battery pack's mA hour. In other words, to charge a 2000 mA battery pack, you usually choose a CC charger with a rated output of 200 mA or less (2000x0.1u003d200). The reason is that the charging rate of 0.1°C is usually not enough to keep the Ni-MH battery overheating after being fully charged. In short, if an ACC charger can supply at least the same voltage as a full charge after charging, as long as the charger can adjust the current, Ohm's law can handle the voltage adjustment. In other words, if the charger's rated voltage is higher than the voltage you want (within a reasonable range), it will usually work. If it can adjust the current, but the charger cannot supply enough voltage, it will not be able to charge the battery. package. This means that you can usually use a 6-cell charger to charge a 4-cell battery pack, or an 8-cell charger to charge a 6-cell battery pack (as long as the current is appropriate), and vice versa. The problem with charging at 0.1 degrees Celsius is that it takes up to 12 hours to charge a depleted battery pack. Charging at a higher speed will shorten the time, but if the power is not disconnected after charging, the battery pack may overheat. This problem is more complicated because we did not completely remove our packaging before charging, and it is almost impossible to accurately determine how long the charging will take. If the backpack is not sufficiently ventilated, even at a low rate of 0.1 degrees Celsius, CC charging will cause overheating. The accumulation of heat may be slow, but if there is enough time, it will definitely reach a destructive level. Ni-MH battery peak detection Ni-MH battery voltage shows an interesting characteristic during the charging process: when the battery is fully charged, the voltage actually reaches a peak value and then slightly drops. The voltage drop after the peak value is called the voltage peak value and is measured in millivolts (mV). The peak detection charger monitors the battery pack voltage while charging, and sees enough peak voltage after charging to end the charging cycle or switch to trickle mode. The peak voltage settings of NiMH batteries range from 4mV to 7mV, but it is important to know the consequences of incorrect settings. The high voltage peak setting allows for more complete charging, but the battery pack becomes hotter and the charger may miss the voltage peak event. A lower voltage peak setting may prevent the battery pack from being fully charged and prone to false peak detection (premature termination of the charging cycle), but a lower setting will also cause the battery pack's temperature to drop at the end of the charging cycle. The default peak NiMH voltage setting is almost always too high. 7mV seems to be the standard, and manufacturers do this to prevent complaints about false peak detection. Unfortunately, before using a new or unfamiliar charger to charge your battery, the first thing to do is to use the voltage peak setting of the highly destructive battery, check the settings and adjust the settings. Another important thing about peak detection charging is that at low charging rates, the voltage peaks become less obvious, which is why it is a bad idea to use a peak detection charger to charge NiMH batteries at a rate lower than 0.3C. . In other words, the charger may not be able to detect peaks below 0.3C. Some chargers may even miss the 0.3c peak, so before you become familiar with the charger's peak detection characteristics, pay attention to the temperature. Well, this is all nickel metal hydride battery maintenance. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete.