Battery Charging Reference for the Main Charger
975-0125-02-01 B–3
Bulk Charge
In the first stage—the bulk charge—MS2000 delivers its full-rated output current.
This constant current is delivered to the batteries until the battery voltage
approaches its gassing voltage—typically around 13.5 volts for 12 volt batteries.
The bulk charge stage restores about 75% of the battery’s charge.
The exit from bulk stage to the next stage, absorption, occurs under the following
condition:
•battery voltage is more than the gassing voltage (VG) for a specified amount
of time (3 minute default).
With an AC reconnect to qualified AC from the utility power or a generator
during the bulk stage, the unit will return to the bulk stage. See “AC Reconnect
Summary” on page B–6.
Absorption Charge
During the first part of absorption charge, the MS2000 delivers its full rated
output current until the absorption voltage is reached. At this point, the MS2000
will transition to a constant voltage mode by keeping the charge voltage constant
at the absorption voltage level, and the battery gradually reduces the chargin g
current it demands as the battery attains full charge.
The absorption stage has t he following exit criteria :
•Overall time in absorption timeout (∆TA) has a default of 6 hours.
•Time in constant voltage absorption timeout (∆TCV) has a default of 1 hour.
•Charge current level drops below a specified limit (IH) for a specified amount
of time, which has a default of 2% of C in Ah for 3 minutes.
See “Charge Algorithm Definitions” on page B–5 for more information.
With an AC reconnect during the absorption stage, the unit will transition to the
float stage for three-stage cha rging and no-float stage for t wo-stage charging. See
“AC Reconnect Summary” on page B–6.
Float Charge
In the third stage—the float charge—which is a maintenance mode, the output
voltage of the charger is reduced to a lower level, typically about 13.5 (VF1) volts
to maintain the battery’s charge without losing electrolyte through gassing.
In the float mode, the cha rger will initiate a new thr ee-stage charge cycle under
any of these conditions:
•any battery drops below 12.5 VDC for 15 minutes (VF2)
•21 days have passed from the time the charger completed Absorption (∆TF)
With AC reconnect during this stage, the unit will return to the float stage. See
“AC Reconnect Summary” on page B–6.