Alpha Technologies XM3-HP Series - Technical Manual - Manual (Page 21)

21 017-882-B0-001 Rev. C2 (10/2013)
1.0
Introduction
1.2 Theory of Operation, continued
1.2.3 Charger Modes of Operation, continued
5-Stage Battery Charger (BULK/ACCEPT/REFRESH/FLOAT/REST):
This preset value is applied to AlphaCell HP batteries when selected in the Smart Display Menu.
REST: Charger is turned off (if ENABLED) and leaves the batteries without external voltage
applied on the battery. Removing charged voltage and allowing the battery to sit in an open
circuit environment maximizes the battery life by eliminating the chance of overcharging individual
cells inside the 12V battery.
If the Smart AlphaGuard (SAG) is installed and the battery harness is connected, the unit will not
go into REST mode until the SAG indicates that any batteries are less than or equal to 0.3V out of
balance, or until 4 days per string has elapsed, whichever comes first after the 6 hour float period.
After any discharge/recharge cycle, once the charger reaches FLOAT mode, it will wait 24 hours
in FLOAT mode before going to REST mode. On a daily basis, without any discharge cycle, the
batteries will be in FLOAT for 25% and REST (charger off) for 75% (6 hours float, 18 hours rest).
REST mode is terminated if voltage drops to less than 2.12VPC. Upon exiting REST mode due
to a voltage below 2.12VDC, a BULK/ACCEPT cycle will be initiated.
The battery charger voltage is temperature-compensated at -0.004VDC per cell per degree C to
ensure a safe battery cell voltage and to maximize battery life.
Fig. 1-4, 5-Stage Charger Modes
BULK
Constant
Current Mode
(10A max) until
battery voltage
reaches the
ACCEPT level
(2.40V/cell)
ACCEPT
Constant Voltage
Mode (2.40V/cell)
until battery current
demand drops below
.5A or time out based
on 4 minutes per Ah
battery capacity
FLOAT
Constant
Voltage
Mode
(2.27V/cell)
Initial 24
hours
REFRESH
Constant
Voltage
Mode
(2.45V/cell)
for 30
minutes
REST
Charger Off
Open Circuit
Voltage
18 hours
Battery Voltage
Battery Current
FLOAT
AND REST
CYCLES
Charger off for
18 hours
Float for 6
hours
1.0 Introduction, continued