Open circuit voltage (OCV): when the battery does not discharge, the potential difference between the two poles of the battery is called open circuit voltage. The open circuit voltage of the battery will vary according to the materials of the positive and negative electrodes of the battery and the electrolyte. If the materials of the positive and negative electrodes of the battery are exactly the same, the open circuit voltage will be the same regardless of the size of the battery and the change of the geometric structure.
Depth of discharge (DoD): in the process of using a battery, the percentage of the discharged capacity of the battery in its rated capacity is called discharge depth. There is a deep relationship between the discharge depth and the charging life of the secondary battery. The deeper the discharge depth of the secondary battery, the shorter the charging life. Therefore, the deep discharge should be avoided as far as possible.
Energy density: the energy released by the average unit volume or mass of a battery. Generally, under the same volume, the energy density of Li ion battery is 2.5 times that of Ni Cd battery and 1.8 times that of Ni MH battery. Therefore, when the battery capacity is equal, the volume and weight of Li ion battery will be smaller and lighter than that of Ni Cd and Ni MH battery.
Cycle life: the capacity of rechargeable battery gradually decreases to 60% - 80% of the initial capacity under repeated charging and discharging.
Over discharge: in the process of discharge, if the battery exceeds the terminal voltage of battery discharge, and continues to discharge, it may cause the increase of internal pressure of battery, damage the reversibility of positive and negative active substances, and significantly reduce the capacity of battery.
Overcharge: when the battery is fully charged, if it continues to charge, it may lead to the increase of internal pressure, deformation and leakage of the battery, and the performance of the battery will also be significantly reduced and damaged.
Self discharge: no matter whether the battery is used or not, it will cause the loss of power for various reasons. If calculated in a month, the self discharge rate of Li ion battery is about 1% - 2%, and that of Ni MH battery is about 3% - 5%.
Cut off discharge voltage: when the battery is discharging, the voltage drops to the lowest working voltage which is not suitable for further discharging. According to different battery types and different discharge conditions, the requirements for the capacity and life of the battery are also different, so the specified discharge termination voltage of the battery is not the same.
