There  are three types of batteries in UPS applications: open liquid lead-acid  batteries, maintenance-free batteries and nickel-chromium batteries. UPS manufacturers are equipped with the battery is generally  maintenance-free battery, the following describes the advantages of  maintenance-free batteries, the use of features and maintenance:
Maintenance-free  batteries, also known as valve-regulated sealed lead-acid batteries,  compared with other batteries for UPS, the advantages of liquid without  maintenance, can be transported in full charge state, without special  maintenance, the disadvantage is not timely Restorative  charge will damage the battery, the temperature is more sensitive,  shorter life, more expensive than the open-type lead-acid batteries. The following guidelines apply when using maintenance-free batteries:
1,  sealed battery allows the operating range of 15 degrees -50 degrees,  but 5 degrees -35 degrees within the use of extended battery life. At minus 15 degrees below the battery chemical composition will change and can not charge. The  highest lifetime is achieved with temperatures in the range of 20  degrees to 25 degrees C. Battery life at low temperatures will result in  longer life but lower capacity, at higher temperatures, higher capacity  but shorter lifetimes. Battery life and temperature relationship can refer to the following  rules, the temperature exceeds 25 degrees Celsius, each 8.3 degrees high  battery life will be reduced by half.
2, maintenance-free design of the battery charge voltage of 2.3V / section. 12V battery is 13.8V. In  the case of 120-cell series, the temperature is higher than 25 degrees  Celsius, the temperature of the floating charge voltage should be  lowered for each degree of 3MV. The same temperature every degree to avoid charging low voltage should be raised 3MV. The discharge termination voltage is 1.67 V per full load (<30 min). In the case of low discharge rate (small current long discharge) to  rise to 1.7V-1.8V per section, APC SYMMETRA charge voltage can be  adjusted according to the load.
3, after the end of the battery if the battery is not recharged within 72 hours. Sulfate will be attached to the plate insulation charge, and damage the battery.
4,  the battery charge in the float or when the internal battery gas  generated in the negative plate electrolysis into water, so as to  maintain the capacity of the battery and do not have external water. But the corrosion of the battery plate will reduce the battery capacity.
5, the battery separator life at an ambient temperature of 30-40 degrees, only 5-6 months. Long-term storage of the battery must be charged once every 6 months. Batteries must be stored in a dry, cool environment. The self-discharge rate of the maintenance-free battery in a 20 degree  environment is 3-4% per month and varies with temperature.
6, maintenance-free batteries are equipped with safety valve, when the  battery internal pressure to a certain extent, when the safety valve  can automatically eliminate excess gas, the internal pressure relief  valve will automatically resume.
7,  the cycle life of the battery (charge and discharge life) depends on  the discharge rate, depth of discharge, and rechargeable rechargeable  way, the most important factor is the depth of discharge. In the discharge rate and time, the more shallow the depth of discharge, the longer the battery life cycle. Maintenance-free batteries at 25 degrees 100% deep discharge cycle life of about 200 times.
8, the battery life at the end of the performance of the capacity  attenuation, internal short circuit, shell deformation, plate corrosion,  open circuit voltage decreases.
9, IEEE defines the end of battery life for the capacity of less than 80% of nominal capacity AH. Nominal  capacity and actual backup time non-linear relationship, the capacity  to reduce the corresponding back-up time by 20% will be reduced a lot. Some UPS manufacturers define battery life to end with capacity drops to 50-60% of nominal capacity.
10, the absolute prohibition of different capacities and different  manufacturers of battery mix, otherwise it will reduce battery life.
11, if the two groups of batteries used in parallel, should ensure that the battery connection, bus impedance the same.
12, maintenance-free battery means that you can not add fluid, but  regularly check whether the cracks in the casing, electrolyte leakage is  still necessary.
3: UPS commonly used batteries
The majority of computer centers are generally selected  maintenance-free batteries, maintenance more convenient, but also need  to do the following:
1: every three to four months to discharge once to prevent oxidation of the plate.
2: The ambient temperature should be maintained at 20-25 degrees.
3: The connection can not be too tight and too loose, need regular checks.
4: The use of three years after the need to promptly check replacement.