ChargeMaster Plus 12/75-3, 12/100-3, 24/40-3, 24/60-3 – User and Installation Manual
21
5.4 The 3-step+ charge process
Battery charging is accomplished in three automatic
stages:
BULK
,
ABSORPTION
and
FLOAT
.
The first step is the
BULK
phase, in which the output
current of the charger is 100%, and the greater part of the
capacity of the battery is rapidly charged. The current
charges the batteries and gradually the voltage rises to the
BULK
voltage 14.25V respectively 28.5V at 25°C/77°F.
The duration of this phase depends on the ratio of battery
to charger capacity, and the battery state of charge.
Figure 6: 3-step charge process
The
BULK
phase is followed by the
ABSORPTION
phase.
Absorption charging starts when the voltage on the
batteries has reached the
BULK
voltage, and ends when
the battery is completely full. Battery voltage remains
constant at 14.25V/28.5V at 25°C/77°F throughout this
stage, and the charge current depends on the degree to
which the battery was initially discharged, the battery type,
the ambient temperature, etc. With a flooded battery this
stage lasts approx. 4h, with gel and AGM around 3h. Once
the battery is 100% full, the ChargeMaster Plus
automatically switches over to the
FLOAT
phase. In
FLOAT
,
the ChargeMaster Plus switches to a stabilized
13.25V/26.5V (Flooded), 13.8V/27.6V (Gel/AGM) or
13.5V/27V (MLI) at 25°C/77°F.
Connected DC loads are powered directly by the charger.
If the load exceeds the charger capacity, the required
additional power comes from the battery, which will be
progressively discharged until the charger automatically
switches back to the bulk phase. Once consumption
decreases, the charger goes back to normal operation of
the 3-step charge system.
As the ChargeMaster Plus is equipped with a 3-step+
charge system, the batteries can also remain connected to
the ChargeMaster Plus during winter. One hour every 14
days the charger automatically switches to absorption to
keep the battery running properly and prolong its life span.
The three-step plus charge system is also safe for all the
connected equipment. See also the 3-Step+ charging
characteristics of flooded batteries on page 27.
5.4.1 Charge voltages
Bulk
Absorption
Float
AGM or GEL
14.25 / 28.5 14.25 / 28.5 13.80 / 27.6
Flooded or
AGM spiral
14.25 / 28.5 14.25 / 28.5 13.25 / 26.5
Flooded traction 14.55 / 29.1 14.55 / 29.1 13.25 / 26.5
Flooded calcium 14.65 / 29.3 14.65 / 29.3 13.30 / 26.6
MLI
14.25 / 28.5 14.25 / 28.5 13.50 / 27.0
5.4.2 Pre-float
The ChargeMaster Plus can automatically switch each
individual output from absorption to pre-float stage. In pre-
float, the charge voltage is 0.7V lower than in absorption
stage. Pre-float ensures batteries that are nearly full don’t
receive the higher charge voltage needed in the
absorption stage. This prevents over-charging, extending
the lifespan of the batteries
.
5.4.3 Temperature compensated charging
By installing the battery temperature sensor, the charge
voltages are automatically adapted for deviating
temperatures.
C
har
ge v
ol
tage (
V)
Battery temperature (°C)
Figure 7: Temperature compensated charging
When the battery temperature is low, the charge voltage
increases. On the other hand, when the battery
temperature is high, the charge voltage is decreased.
Overcharge and gassing are prevented this way. This will
extend the life of your batteries.
5.4.4 Flat battery support
The ChargeMaster Plus automatically detects a flat battery
and will initiate the flat battery charge curve described in
the following table.
UBat Voltage
Output power
12V
24V
0.00V – 2.50V
0.00V – 5.00V
15%-30% of I
max
12V
24V
2.50V – 8.00V
5.00V – 16.00V
25% of I
max
12V
24V
8.00V – 10.00V
16.00V – 20.00V
linear from 25% - 100% of
I
max
12V
24V
10.00V – 14.25V
20.00V – 28.50V
100% of I
max
12V
24V
>14.25
>28.50
Limited by P
max