There are three types of batteries commonly used in UPS power applications: open liquid lead-acid batteries, maintenance-free batteries, and nickel-cadmium batteries. Factors that affect battery life, different types of batteries also have their own advantages and disadvantages. The batteries currently provided by UPS manufacturers are generally maintenance-free batteries. The following mainly introduces the characteristics of the three types of batteries:
1: Open type liquid lead-acid battery
According to this nature, this type of battery can be divided into two types: 8-10 years and 15-20 years. Since the sulfuric acid electrolysis of this battery will produce corrosive gas, this type of battery must be installed in a ventilated room away from precision electronic equipment, and the battery room should be paved with anti-corrosion tiles.
Due to evaporation, open batteries need to measure specific gravity regularly, add acid and water. This battery can withstand high temperature, high pressure and deep discharge. The battery room should be non-smoking and use open battery racks.
This battery cannot be transported after being charged, so it must be charged after installation on site. The initial charge usually takes 55-90 hours. The normal voltage of each cell is 2V, and the initial charging voltage is 2.6-2.7v.
Also known as valve-regulated sealed lead-acid batteries, the following principles must be followed during use and maintenance:
a: The permissible operating range of sealed batteries is 15 degrees to 50 degrees, but using within 5 degrees to 35 degrees can extend the battery life. Below minus 15 degrees, the battery chemical composition will change and cannot be charged. Using within the range of 20 degrees to 25 degrees will achieve the highest life. The battery will have a long life but lower capacity when running at low temperatures, and a higher capacity but a shorter life when running at high temperatures.
b: The relationship between battery life and temperature can refer to the following rule. When the temperature exceeds 25 degrees Celsius, the battery life will be reduced by half for every 8.3 degrees increase in temperature.
c: The design float charge voltage of maintenance-free battery is 2.3V/cell. The 12V battery is 13.8V. CSB recommends 2.25-2.3V per cell. When 120 cells are connected in series, the float charge voltage should be reduced by 3MV for every degree increase in temperature after the temperature is higher than 25 degrees Celsius. Similarly, the voltage should be increased by 3MV for every degree increase in temperature to avoid undercharging. The discharge termination voltage is 1.67V per cell under full load (<30 minutes). Under low discharge rate conditions (low current long-term discharge), it should be increased to 1.7V-1.8V per cell. APCSYMMETRA can adjust the charging voltage according to the load.
d: If the battery is not recharged within 72 hours after discharge, sulfate will adhere to the plates and insulate the battery, thus damaging the battery.
e: When the battery is floating charged or equalized charged, the gas generated inside the battery is electrolyzed into water on the negative plate, thereby maintaining the battery capacity without adding water. However, the corrosion of the battery plate will reduce the battery capacity.
f: The battery separator life is only 5-6 months at an ambient temperature of 30-40 degrees. Batteries stored for a long time must be charged every 6 months. Batteries must be stored in a dry and cool environment. The self-discharge rate of maintenance-free batteries at 20 degrees is 3-4% per month and varies with temperature.
g : Maintenance-free batteries are equipped with safety valves. When the internal air pressure of the battery rises to a certain level, the safety valve can automatically discharge excess gas. When the internal air pressure is restored, the safety valve will automatically recover.
h: The cycle life (number of charge and discharge cycles) of a battery depends on the dry discharge rate, depth of discharge, and the most important factor in the recovery charging method, which is the depth of discharge. When the discharge rate and time are constant, the shallower the discharge depth, the longer the battery cycle life. The maintenance free battery has a lifespan of approximately 200 cycles under 100% deep discharge at 25 degrees Celsius.
i: When the battery reaches the end of its life, it will show capacity attenuation, internal short circuit, shell deformation, plate corrosion, open circuit voltage drop.
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