Monday, December 27, 2010

【 Weak current College 】 impact battery life of the main factors and considerations 】


1 preface
UPS system battery is an important component, it merits a direct relationship to the entire UPS system reliability. No matter how advanced UPS design, function and how complete, once the batteries fail, then good UPS is unable to provide uninterruptible power supply. Please do not use Pidgin cheap, poor quality lead-acid battery, which can affect the reliability of the entire UPS system, and will thus lead to greater losses.
Battery is the entire UPS systems mean time between failures (MTBF) is the shortest part. If you are able to correct use and maintenance, will be able to extend its service life, the life will be shortened considerably. Therefore, we must understand the basic principles and battery usage considerations.
2 lead-acid battery
Battery types generally can be divided into lead-acid batteries, lead-acid battery and nickel-cadmium batteries, considering the load conditions, the use environment, service life and cost and other factors, UPS generally opt for valve-regulated lead-acid battery. Its main characteristic is in charge of positive plates produced oxygen, by chemical reaction at the cathode on restore into water, used in floating charge lifetime maintenance without adding water, also known as maintenance-free lead-acid batteries. Maintenance-free battery only with the general use than eliminating the add pure water or distilled water, adjust the electrolyte level of work, not waive all maintenance work. On the contrary, to achieve uninterrupted power supply UPS, we want more detail maintenance and upkeep of good lead-acid battery.
3 impact on the life of the main factors and considerations
Here's what impact the battery life of the main factors and use of matters:
⑴ environmental effects of temperature on the battery. Ambient temperature too high, will enable battery overcharge produce gas, environment temperature is too low, it makes the battery charge is insufficient, this will affect battery life. Therefore,General requirements and environmental temperature 25℃, UPS floating charge voltage value is set according to the temperature. The actual application, the battery is normally 5 ℃-35 ℃-wide charge, lower than 5 ° c or higher than 35 ° c will greatly reduce the battery's capacity, shorten battery life.
⑵ discharge depth on the battery life is also very large. Battery discharge depth deeper, its recycling, the fewer times, when in use to avoid deep discharge. Although the UPS has the protection function battery low, generally single battery discharge to 10.5V left, UPS will automatically shutdown. However, if the UPS is in a no-load speed of discharge or discharge, can have a depth of discharge of the battery.
⑶ battery in the storage, transportation, installation, will lose part of self discharge. Therefore, before the system is put into use after installation must be set according to the judgement of the open-circuit voltage of battery battery remaining capacity, and uses different methods to supplement the charge on the battery. On standby pending battery every three months to conduct a supplementary charge. You can measure battery open-circuit voltage to determine if the battery is good or bad. To 12V battery, for example, if the open-circuit voltage higher than 12.5V, indicates that the battery has 80 percent of energy storage, if the open-circuit voltage lower than 12.5V, you should immediately be supplementary charge. If open-circuit voltage lower than 12V, battery storage power less than 20 percent, the battery was used.
⑷ battery charging and discharging current General to C to represent the actual value of the C and battery capacity. For example, 100AH battery, C = 100A. Maintenance-free lead-acid batteries Panasonic's best charging current is about charging current 0.1C cannot be greater than 0.3C. Charging current is too large or too small can affect battery life. Discharge current General requirements between the 0.05C ~ 3C, UPS in normal use canmeet this requirement, but also to prevent the occurrence of unexpected situations, such as battery, short circuit, etc.
⑸ charging voltage. Due to the UPS battery is an alternate way of working, the commercial power supply under normal circumstances is charging status, only the outage will discharge. To extend battery life, the charger generally use the UPS ·drive control after the battery is fully converted into floating State, each section is floating charge voltage set to 13.6V. If the charging voltage of the battery overcharge, on the other hand makes the battery charge is low. Charging voltage anomalies is probably caused by the battery is incorrectly configured, or the charger fault. Therefore, when you install the battery, it is important to note that the number of battery specifications and accuracy, with different sizes, different lot numbers of batteries don't mix. Do not use external charger, and poor quality charger installed thermal issues to consider when. At present, in order to further improve the battery life, advanced ups are an ABM (AdvancedBatteryManagement) three phase intelligent battery management programmes, i.e. charging into initialization and float charging and rest in three stages: the first stage is constant current charging, the battery capacity is filled to 90%; the second stage is a floating charge, charge the battery to 100% of capacity, and then stop charging; third stage is the natural discharge, at this stage, the battery use its leakage current of discharge, up to the minimum required voltage, and then repeat the previous three phases. In this way changes the previous one is fully charged, the battery is still a day 24-floating State, thus extending the battery life.
⑹ maintenance-free battery electrolyte absorption due to the adoption, in the normal use of the system does not produce any gas, but if the user used incorrectly, causing the battery overcharge, gas, battery internal pressure will increase, the battery on thepressure valve top, serious cause the batteries to burst.
⑺ UPS running process, to monitor the battery's Terminal voltage values, floating charge flow values, each battery voltage, battery and DC bus ground resistance and insulation.
⑻ don't separate increase or decrease the battery pack in single cells of load, this will result in single battery capacity imbalances and charging of heterogeneity, and reduce the battery life.
⑼ batteries should be installed on a clean, cool, ventilated, dry place, and to avoid the Sun, heater or other radiation source. The battery should just stand placement, not tilt angle. Each battery is securely attached to between terminals.
⑽ regular maintenance. Battery in use after a certain period of time should be regularly checked, such as observation of their appearance is abnormal, measure the voltage of the battery is average, and so on. If you live long, the battery will remain in charge status, which will make the battery of the activity of variation. Therefore, even without power, UPS also need periodic discharge test so that the battery remains active. Discharge test generally three-monthly, is the UPS load-the best in more than 50%, and then disconnect the mains, the UPS is in battery discharge status, discharge duration depending on the battery capacity is typically a few ms to dozens of ms, inverter, after continued to charge the battery.
4 closing
Understand and clearly affect the battery life of the main factors and in the use of matters on our UPS system on the proper use and maintenance of lead-acid batteries have a very big help. I hope everyone in their day-to-day work correct use and maintenance of good lead-acid battery, so it can get a more rational use.



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