How to judge the charging time of Ni-MH battery

How long is the charging time of NiMH batteries? It is a lot of people’s doubts, because nickel-metal hydride batteries cannot judge whether the battery is fully charged by voltage. Nickel-metal hydride batteries are different from lithium batteries. When a lithium battery reaches a specified voltage, it represents a signal that the lithium battery is fully charged, while nickel with different levels of old and new The conditions required for a full charge of a hydrogen battery are different, which is one of the characteristics of a nickel-hydrogen battery. How long does it take to charge a Ni-MH battery? In order to ensure the recycling of the newly purchased nickel-metal hydride batteries, the first charging time is slightly longer. Because the smart Ni-MH battery charger uses the -△V signal to determine whether the Ni-MH battery is fully charged, the newly purchased Ni-MH battery may not have a -△V signal when it has been stored for a certain period of time when it is charged for the first time. It is detected, so the charger will continue to charge with a small current, and will not stop until the charging time set by the charger, theoretically. At this time, the Ni-MH battery has actually been overcharged, but this will not have much impact on the Ni-MH battery, because the Ni-MH battery will convert the excess power into heat and consume it. Therefore, when a newly purchased Ni-MH battery is charged for the first time, the battery will be relatively hot. How long it takes for the Ni-MH battery to be fully charged depends on the capacity of the battery and the power consumption of the charger. In addition, it also needs to see whether the Ni-MH battery is in a normal state. When the Ni-MH battery is stored for more than half a month, the battery may enter Sluggish state, of course, the better the quality of the Ni-MH battery will be longer, the sluggish state of the battery using a smart Ni-MH battery charger is of little practical significance, when there is no -△V signal, the charger is usually time forced to stop It usually takes 5-10 hours to charge. Ni-MH batteries under normal conditions can be fully charged in 2 hours at the fastest using a fast charger. Individual ultra-fast charging may be fully charged in 1 hour, but Ni-MH batteries are not suitable for ultra-fast charging. Overheated batteries will evaporate the water inside the battery and shorten the battery life. How to judge how long it takes to charge a Ni-MH battery? 1) The nominal capacity of the battery, the larger the capacity, the longer the charging time is required; 2) When charging several batteries at the same time, and some Ni-MH batteries are charged, the charging time of two batteries and four batteries is different, charge two batteries It is twice as fast as charging four cells; 3) The current that the charger can output is faster when the current is large, and slow when the current is small; 4) Whether the battery is left, if it is completely empty, the charging time will be longer, if it is still If there is remaining power, the charging time is shorter. There is a formula for charging Ni-MH batteries: battery capacity (milliamp hours) ÷ charging current (milliamps) u0026 TImes; 1.2~1.5 u003d the time required for the battery to be fully charged (hours). Due to different chargers, the magnitude of the charging current is also different. The charging time is generally indicated on the charger manual. It takes 10 to 20 hours for standard charging, 6 to 8 hours for fast charging, and 1 to 2 hours for fast charging. The normal charging time is mainly related to the charging current of the charger used. Under normal circumstances, the Ni-MH battery charger can automatically stop when it is fully charged. For example, the battery used can be fully charged in one hour with a 1000mA charger. Instructions for charging Ni-MH batteries; the working time of Ni-MH batteries (the number of recharges and the number of discharges) mainly depends on the working conditions. The operating time decreases as the depth and discharge rate increase. The running time depends on the charging speed and control method. According to the type of Ni-MH battery, working mode and working conditions, the battery can provide 500-1000 discharge cycles, the discharge depth is 80%, and the service life is 35 years. To ensure reliable operation of Ni-MH batteries during the warranty period, please follow the recommendations and manufacturer's instructions. Should pay attention to the temperature environment. Avoid over discharge (less than 1V) and short circuit. Ni-MH batteries should be used according to the application. Do not directly solder unused batteries. Ni-MH batteries are more sensitive to overcharging than Ni-Cd. Overcharging will cause thermal acceleration. Charging is usually carried out for 15 hours at a current of ICu003d0.1°C. Current Icu003dcompensation charge that occurs for more than 30 hours at 0.01-0.03°C. Ni-MH batteries with many active electrodes can be accelerated (4-5 hours) and fast-charged (1 hour). If there is such a charge, the process is controlled by the temperature change ΔT and voltage ΔU and other parameters. For example, laptops and mobile phones currently mainly use lithium-ion and lithium polymer batteries, but fast charging is used for nickel-metal hydride batteries that power laptops, mobile phones, and power tools. The first step of fast charging (1C or higher) is to charge at 0.1C for final charging. It is also recommended to use a charging method of 0.05-0.02C charging with compensation charging. Information on how to charge NiMH batteries is usually included in the manufacturer's instructions. Due to the release of oxygen at the anode, the amount of electricity (Q3) delivered during charging is greater than the discharge capacity (Cp). In this case, the return capacity (100Cp/Q3) of the disc and cylindrical Ni-MH batteries are 75-80% and 85-90%, respectively. Charge and discharge control: To avoid overcharging of Ni-MH rechargeable batteries, the following charging monitoring methods can be used with appropriate sensors installed in rechargeable batteries or chargers. A method of charging termination at absolute temperature (Tmax): During the charging process, the battery temperature is continuously monitored and the fast charging is stopped when the maximum value is reached. A method to terminate the charge relative to the temperature change rate ΔT/ΔT: When this method is used, the slope of the battery temperature curve will be continuously monitored during the charging process. When this parameter is higher than a certain set value, the charging will stop. When the battery is fully charged, the oxygen cycle begins, the temperature starts to rise, and the voltage drops. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous article: The 'full life cycle management' of lithium batteries can solve many problems of lithium-ion batteries