APC battery

http://www.schneider-electric.co.th/support/index?page=content&country=th&lang=zh&id=FA158934

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Most APC batteries should last three to five years. There are many factors which affect Battery life including environment and number of discharges. Below are some guidelines to ensure optimum life expectancy:

1. Make sure that you keep your APC UPS in a cool, dry location with plenty of ventilation. Ideally, the temperature where your UPS is kept should not exceed 75° F (24° C). Also, for ventilation purposes, leave roughly one to two inches on each side for proper airflow.

2. The optimum operating temperature for a lead-acid battery is 25 Deg C (77 Deg F). Elevated temperature reduces longevity. As a guideline, every 8 Deg C (15 Deg F) rise in temperature will cut the battery life in half. A battery which would last for 5 years at 25 Deg C (77 Deg F), will only be good for 3 years if operated at 33 Deg C (95 Deg F). Keep in mind that the battery temperature inside your UPS will always be warmer than the ambient temperature of the location where the UPS is installed.

3. Only perform runtime calibrations on your UPS one or two times a year, if necessary. Some of our customers want to check their systems to verify that their runtime is sufficient. However, consistently performing these calibrations can significantly decrease the life expectancy of your APC battery.  

4. Do not store APC batteries for extended periods of time. New batteries can be stored for 6 to 12 months from date of purchase. After this period, the battery should be used or it will lose a great deal of its charge . It is not advisable to store batteries that have already been in use.

5.  As the load increases on your UPS, the runtime decreases. It is not recommended that the load exceed 80 percent of the UPS unit’s rated capacity. In the event of a power failure, a UPS loaded to full capacity will discharge the battery very quickly and there is a potential that the life expectancy of the battery will be significantly reduced.
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SYBT4: Battery Module for Symmetra PX, Smart-UPS VT or Galaxy 3500
Expected Battery Life (years)  ...  3 - 5