HOW IT WORKS
EN / Mass Combi 12/2500-100; 24/2500-60; 48/2500-35; 48/5000-70 / May 2010 7
3 HOW IT WORKS
This chapter describes the various applications of the
Mass Combi series from Mastervolt.
The Mastervolt Mass Combi is a battery charger, a
powerful sine wave inverter and an AC transfer system in
one compact enclosure. The three-step Plus charging
method guarantees that the batteries are always charged
100% The pure sine wave inverter assures that the AC
output voltage is perfectly reliable even when limited
external AC power is available. External AC power can be
supplied by a public grid or a generator. DC power can be
delivered by charged batteries.
3.1 THE BATTERY CHARGER
The built-in battery charger is electronically controlled. It is
designed for optimal recharging of both wet cell, gel cell
and AGM deep cycle batteries. Battery charging is
accomplished in three automatic stages: BULK,
ABSORPTION and FLOAT. With an external AC source
connected, the Mass Combi charger also serves the
functions of an AC to DC converter to supply DC loads
which are connected to the battery. Simple, automatic
operation is made possible by the microprocessor that is
the brain of the inverter/charger combination. In most
cases, the unit is left on and no attention or maintenance
is required.
3.1.1 Three step Plus charge system
See figure 2. The first step of the three step Plus charge
system 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 absorption
voltage of 14.4, 28.8 or 57.6 V (12, 24 resp. 48V models)
@ 25°C / 77°F.
The duration of this phase depends on the ration of battery
to charger capacity, and naturally also on the degree to
which the batteries were discharged to begin with.
The bulk phase is followed by the absorption phase.
Absorption charging starts when the voltage on the
batteries has reached 14.4, 28.8 or 57.6 V (12, 24 resp.
48V models) @ 25°C / 77°F, and ends when the battery is
completely full. Battery voltage remains constant at 14.25,
28.5, 57 V (12, 24 resp. 48V models) @ 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, and so on. With
a wet cell battery this stage lasts some four hours, with gel
and AGM around three. Once the battery is 100% full, the
Mastervolt charger automatically switches over to the float
phase.
During the float phase the Mass Combi switches to 13.25,
26.5 or 63 V (12, 24 resp. 48V models) @ 25°C / 77°F and
stabilises this voltage to maintain the batteries in an
optimum condition. Connected DC-loads are powered
directly by the charger. If the load is higher than 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 three-step charge system.
As the Mass Combi is equipped with a three-step Plus
charge system, the batteries can also remain connected to
the Mass Combi in winter. One hour every 12 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 section 10.4 for detailed characteristics of the
three step Plus charge system.
Figure 2:
Three step charge system
CHARGE CURRENT
BATTERY VOLTAGE
BULK
ABSORPTION
FLOAT
TIME
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