Introduction - NorthStar NSB12-310 Applications Manual

1

Introduction

UPS batteries from NorthStar Battery (NSB) Compa-
ny provide excellent high-rate discharge and recharge
performance for mission critical applications. Ab-
sorbed-Glass-Microfibre (AGM) technology is utilized,
which means the electrolyte is fully absorbed in a very
fine glass mat. This allows for very efficient recombina-
tion of any gas generated during the charging process.
The release of gas from NSB batteries is very low, hence
natural ventilation is sufficient for both cooling and the
dissipation of any gas formed during inadvertent over-
charge. Hence, NSB UPS batteries can be used safely in
offices and with mains equipment.
NSB UPS batteries excel at providing both short duration
high amperage pulses, low rate long duration deep dis-
charges and high cyclic capabilities.
2 Charge
In order to maximize the life of the UPS batteries, it is
recommended that the battery be fully recharged fol-
lowing an outage.
2.1 Determining State of Charge (SOC)
The SOC of a battery can be determined by measuring
the open-circuit-voltage (OCV) of the battery. If the bat-
tery has been recently recharged, a rest period of at
least 3 hours is required before taking measurements.
The relationship between OCV and SOC for the NSB UPS
batteries is displayed in the following graph:
A fully charged NSB UPS battery will measure
approximately 13.0 V.
2.2 Thermal Compensation
The optimum level for float charging the NSB UPS
batteries is 2.27 volts/cell at +25°C (+77°F). If the battery
temperature increases above this level, a thermal
compensation of -2 mV/cell/°C is recommended.
Conversely, if the temperature decreases below 25°C,
Form: SES-541-01711
the voltage should be increased by 2 mV/cell/°C. The
graph below shows values for an individual cell.
2.3 Fast Charging
If the charging system is properly sized, a fast charging
regime will serve to minimize the time needed to
recharge NSB UPS batteries. This can be beneficial, for
maximizing the cycle life of the product.
In a fast charging regime, the charging system is assumed
to be adequately sized to provide the power needed (see
Section 2.4). Fast charging is conveniently achieved by
using a higher charging voltage. This method maintains
the charge current at a high level during the second half
of the charging process. As a result, a discharged battery
bank will be returned to a fully charged state in a shorter
time.
The increased voltage setting is known as boost voltage.
In a fast charging regime the boost voltage shall be
2.41 Volts/Cell provided that the temperature is a
nominal +25°C (+77°F). The following graph shows the
recommended charging profile following a 100% DOD
cycle:
Issued: 12-08-16 ECO-101191