battery related concepts
1. Voltage (V)
①Open circuit voltage: refers to the voltage of the battery when it is not connected to an external circuit or external load. The open circuit voltage has a certain relationship with the remaining energy of the battery, and the power display uses this principle.
②Operating voltage: It refers to the potential difference between the positive and negative electrodes of the battery when the battery is under operating conditions, that is, when there is current flowing in the circuit, also known as the load voltage. Under the condition of battery discharge operation, when the current flows inside the battery, it is necessary to overcome the resistance of the internal resistance, so the operating voltage is always lower than the open circuit voltage.
③Discharge cut-off voltage: refers to the voltage reached when the battery is discharged after being charged and overcharged (if it continues to discharge, it is excessive discharge, which will damage the life and function of the battery).
④Charging constraint voltage: the voltage that changes from constant current to constant voltage charging during the charging process.
2. Battery capacity (Ah)
① Definition: The battery capacity refers to the amount of electricity that the battery can store. The capacity is an important target of the battery's electrical function, which is determined by the active material of the electrode.
②Unit: The capacity is indicated by C, and the unit is indicated by Ah (ampere hour) or mAh (milliampere hour).
③Formula: C=It, that is, battery capacity (Ah) = current (A) x discharge time (h).
④ Example: A battery with a capacity of 10 amps can be discharged for 2 hours at 5 amps and 1 hour at 10 amps.
⑤ Influencing factors: The actual capacity of the battery mainly depends on the following factors: the quantity and quality of active materials, and the utilization rate of active materials.
⑥Additional capacity: measured under regular conditions, the battery capacity given by the manufacturer.
⑦Available capacity: The amount of electricity released from a fully charged battery under regular conditions.
⑧Theoretical capacity: Assuming that the active material is completely used, the capacity of the battery that can be released.
3. Battery energy (Wh)
① Definition: Refers to the amount of energy stored in the battery, expressed in Wh
②Formula: energy (Wh) = extra voltage (V) × working current (A) × working time (h).
③Example: The energy of a 3.2V15Ah single cell is 48Wh, and the energy of a 3.2V100Ah battery pack is 320Wh.
Battery energy is an important target to measure the work done by battery-driven equipment, and capacity cannot determine how much work is done.
