Installing the External Batteries (if applicable)
Installing the External Batteries (if applicable)
This section applies to
One 48 V battery string can be connected to
A 48 V battery string consists of either:
•24 Valve Regulated Lead Acid (VRLA) 2 V cells or
•Four VRLA 12 V monoblocs
Because of the wide range of battery types and sizes available, we do not supply batteries with the above mentioned power systems and therefore do not cover battery installation in this guide. Always install batteries according to the relevant battery manufacturer’s instructions.
Battery Sizing
Battery manufacturers provide various types of information for sizing batteries such as constant current discharge and constant power discharge data. Your battery supplier will be able to assist you with sizing the battery for your application.
Before a battery can be sized, the following information is required.
•Required backup time
•Minimum cell voltage (typically 1.83 V per Cell)
•Load profile
•Operating temperature
In telecommunications and data applications most loads are constant power for a specified backup time. Therefore, for sizing a battery for the required backup time, constant power discharge data should be used.
For charging the battery, constant current discharge data should be used. When charging the battery, battery current limit should be used to set the battery charge to no more than the maximum recharge specified by the battery manufacturer.
Batteries for use in North America must be a UL recognized type, category BAZR2.
Battery Location
Valve Regulated Lead Acid (VRLA) batteries emit very small amounts of hydrogen gas into the surrounding atmosphere under normal float charging conditions. For that reason batteries should never be installed in a sealed enclosure or cabinet.
Install the batteries in a
Building air conditioning and ventilation systems already in place for optimum equipment operation and comfort of personnel usually meet or exceed VRLA battery ventilation requirements. For specific battery ventilation requirements, always refer to the battery manufacturer’s installation instructions.
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