Yuasa NP Series, Manual

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Impedance testing can be performed using the Yuasa YPI-2
Impedance/comparator test meter, this form of testing is
non-intrusive and can be performed online with the battery
still connected within its system. (Note: The YPI-2 meter can
Note
The recommended float charge voltage for NP type
batteries at 20°C is 2.275vpc ± 0.005v. this should be the
measured average for the total battery, however when
measured within a battery network or string the allowable
tolerances can be expected between 2.25vpc and 2.3vpc.
CHARGING
not be used where a high AC ripple content exists.) By
using this test method deterioration can be detected with-
out removing the battery from its standby mode.
Correct charging is one of the most important factors to
consider when using valve regulated lead acid batteries.
Battery performance and service life will be directly affected
by the efficiency of the charger selected. The basic charging
methods are:
•
Constant Voltage Charging
•
Constant Current Charging
•
Taper Current Charging
•
Two Stage Constant Voltage Charging
Constant Voltage Charging
Charging at constant voltage is the most suitable and
commonly used method for charging valve regulated
lead acid batteries. Figures 10 - 15 show the charging
characteristics of NP batteries when charged by constant
voltage chargers at 2.275 volts/cell, 2.40 volts/cell and 2.50
volts/cell when the initial charging current is controlled at
0.1C Amps and 0.25C Amps.
Figure 9 shows one example of a constant voltage charging
circuit. In this circuit, the initial charging current is limited
by the series resistance R1.