Common technical parameters of lithium battery UPS. When choosing a lithium battery UPS, when you choose a specific type of lithium battery UPS according to the required field of lithium battery UPS or according to the recommendations of the lithium battery manufacturer, for example, choose a rack UPS or a tower UPS in the computer room. . After selecting the type of lithium battery UPS? After that, more specific parameters are required.
Let's talk about the parameters that you usually look at when you look at lithium battery UPS. Presumably many people have read and listened to these parameters a lot, so they have a good understanding of their general meaning, but they still don't know much about their definitions. Let the editor of Cunneng Electric collect and sort out its specific meaning for everyone to see. The following definitions are mainly collected from Baidu Encyclopedia.
battery capacity
Battery capacity is one of the important performance indicators to measure battery performance. It represents the amount of power released by the battery under certain conditions (discharge rate, temperature, termination voltage, etc.) Ampere·hour is the unit (referred to as A·H, 1A·h=3600C).
The battery capacity is divided into actual capacity, theoretical capacity and rated capacity according to different conditions. The calculation formula of battery capacity C is C=∫t0It1dt (the current I is integrated during the time from t0 to t1), and the battery is divided into positive and negative electrodes.
Q
Nominal voltage is a professional term in physics, which refers to the voltage value corresponding to the nominal operating current of the regulated thermistor at +25°C. At present, the nominal voltage of the most commonly used regulated thermistor is 2 volts, and others include 3 volts, 4 volts, 5 volts, 6 volts, etc. Nominal voltage is also the appropriate voltage approximation to represent or identify a battery, also known as rated voltage, which can be used to identify battery types.
The nominal voltage of a battery is an approximation of the appropriate voltage to represent or identify a battery, also known as the rated voltage, and can be used to identify the battery type. For example, the open circuit voltage of lead-acid batteries is close to 2.1V, and the nominal voltage is 2.0V. The nominal voltage of zinc-manganese dry batteries is 1.5V, the nominal voltage of nickel-cadmium batteries and nickel-hydrogen batteries is 1.2V, and the nominal voltage of lithium-ion batteries is 3.7V.
In fact, the nominal voltage does not refer to the battery voltage, the actual voltage of the battery changes according to the actual capacity of the battery. In the market, the nominal voltage of the same battery may be different in different scenarios or regions, but the battery actually does not change.
Internal resistance of battery
The internal resistance of the battery refers to the resistance of the current flowing through the battery when the battery is working. It includes the ohmic internal resistance and the polarization internal resistance, and the polarization internal resistance includes the electrochemical polarization internal resistance and the concentration polarization internal resistance. resistance.
For lithium-ion batteries, the internal resistance of the battery is divided into ohmic internal resistance and polarization internal resistance. Ohmic internal resistance consists of electrode material, electrolyte, diaphragm resistance and contact resistance of various parts. Polarization internal resistance refers to the resistance caused by polarization during electrochemical reaction, including resistance caused by electrochemical polarization and concentration polarization.
The actual internal resistance of a lithium-ion battery refers to the resistance received by the current flowing through the battery when the battery is working. The internal resistance of the battery is large, and (during the normal use of the battery) a large amount of Joule heat will be generated (according to the formula: E=I^2RT), which will cause the battery temperature to rise, resulting in a reduction in the battery discharge working voltage and shortening of the discharge time, which will affect the performance and life of the battery. cause serious impact.
The precise calculation of the internal resistance of the battery is quite complicated, and it will continue to change during the use of the battery. According to experience, the larger the volume of the lithium-ion battery, the smaller the internal resistance; and vice versa.
Self-discharge rate
Self-discharge rate, also known as charge retention capability, refers to the retention capability of the battery’s stored power under certain conditions when the battery is in an open-circuit state. Mainly affected by the battery manufacturing process, materials, storage conditions and other factors. It is an important parameter to measure battery performance.
The self-discharge size, that is, the self-discharge rate, is related to the solubility of the positive electrode material in the electrolyte and its instability (easy self-decomposition) after being heated. The self-discharge of rechargeable batteries is much higher than that of primary batteries. And different battery types have different monthly self-discharge rates. Generally 10-35% change. During the storage process, self-discharge is accompanied by an increase in the internal resistance of the battery, which will reduce the load capacity of the battery. In the case of a large discharge current, the energy loss changes significantly.
It is not enough to judge the performance of the lithium battery UPS by looking at one of these parameters alone. It is necessary to refer to other technical parameters to comprehensively judge the performance of the selected lithium battery UPS.
