Nickel-metal hydride battery characteristics

Ni-MH batteries have six main characteristics: charging characteristics and discharge characteristics that express operating characteristics, self-discharging characteristics and long-term storage characteristics that exhibit storage characteristics, and exhibit comprehensive cycle life characteristics and safety characteristics. They are all determined by the structure of the battery and are manifested in the environment. The remarkable feature is that it is greatly affected by temperature and current.

1. Charging characteristics: When the charging current of the nickel-hydrogen battery increases and/or the charging temperature decreases, the charging voltage of the battery rises. Generally, a constant current of not more than 1 C is charged at an ambient temperature of between 0 ° C and 40 ° C, and charging between 10 ° C and 30 ° C can achieve a higher charging efficiency.

If the battery is often charged in a high temperature or low temperature environment, the performance of the power battery will be degraded. For fast charging above 0.3C, charging control measures are indispensable. Repeated overcharging will also degrade the performance of the battery, so the protection measures for high and low temperature and high current charging must be in place.

2. Discharge characteristics: The discharge platform of Ni-MH battery is 1.2V. The higher the current, the lower the temperature, the lower the battery discharge voltage and discharge efficiency, and the maximum continuous discharge current of the battery is 3C.

The discharge cut-off voltage of the battery is generally set at 0.9V, and the IEC standard charge and discharge mode is set to 1.0V, because a stable current can be generally supplied below 1.0V, and a slightly smaller current can be supplied below 0.9V. The discharge cut-off voltage of NiMH batteries can be regarded as a voltage range of 0.9V~1.0V, and some batteries can be subscripted to 0.8V. Under normal circumstances, if the cutoff voltage is set too high, the battery capacity cannot be fully utilized, and conversely, it is easy to cause the battery to be over-discharged.

3. Self-discharge characteristics: refers to the phenomenon of capacity loss when the battery is fully charged open storage, self-discharge characteristics are mainly affected by the ambient temperature, the higher the temperature, the greater the capacity loss after storage.

4. Long-term storage characteristics: mainly refers to the power recovery capacity of nickel-metal hydride batteries. After a long period of time (such as one year), the battery capacity may be smaller than the capacity before storage, but after several charge and discharge cycles, the battery can be restored to the capacity before storage.

5. Cycle life characteristics: The cycle life of NiMH batteries is affected by the charge and discharge system, temperature and usage. When charging and discharging according to the IEC standard, a full charge and discharge is the charging cycle of the nickel-hydrogen battery. The multiple charge cycles constitute the cycle life, and the charge-discharge cycle of the nickel-hydrogen battery can exceed 500 times.

6. Safety: The safety performance of nickel-metal hydride batteries is better in battery design. This is of course related to the material materials used, and its structure is inseparable. During use, if the battery is improperly used, causing overcharge, overdischarge, and short circuit, and causing the internal pressure of the battery to rise, then a recoverable safety valve will be opened to reduce internal pressure and prevent the role of battery explosion.

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