© 2010 Magnum Energy, Inc.
3.0 Operation
28
Standby Mode
The MMS Series features an automatic transfer relay and an internal
battery charger when operating in Standby Mode. Standby Mode
begins whenever AC power (shore power or generator) is connected
to the inverter’s AC input. Once the AC voltage and frequency of the
incoming AC power is within the AC input limits, an automatic AC
transfer relay is activated. This transfer relay passes the incoming AC
power through the inverter to power the AC loads on the inverter’s
output. This incoming power is also used to activate a powerful in-
ternal battery charger to keep the battery bank charged in case of
a power failure.
Battery charging
-
The MMS Series models are equipped with an
active Power Factor Corrected (PFC) multi-stage battery charger. The
PFC feature is used to control the amount of power used to charge
the batteries in order to obtain a power factor as close as possible to
1 (or unity). This causes the battery charger to look like a resistor to
the line (forces the charge current waveshape to mirror the voltage
waveshape). This feature maximizes the real power available from
the AC power source (shore power or generator), which translates
into less power wasted and a greater charging capability than most
chargers available today.
When an AC power source is connected to an inverter that has a
battery charger, the inverter monitors the AC input for acceptable
voltage. Once the inverter has accepted the AC input, the AC transfer
relay will close and charging will begin. Once charging, the DC voltage
is monitored to determine the charging stage. If the DC voltage is low
(
≤
12.9 VDC), the charger begins bulk charging. If the DC voltage is
high (>12.9 VDC), the charger skips the initial Bulk/Absorb Charging
stages and goes directly to
fl
oat charging.
The multi-stage charger can use up to
fi
ve different charging stages
to help monitor and keep the batteries healthy.
The
fi
ve stages
include an automatic 4-stage charging process (Bulk, Absorb, Float,
and Full Charge), and a manual Equalization (EQ) charge stage.
The
automatic 4-stage charge process provides complete recharging and
monitoring of the batteries without damage due to overcharging (see
Figure 15). The Equalization stage (requires
the ME-RC50 remote)
is used to stir up strati
fi
ed electrolyte and reverse any battery plate
sulfation that might have occurred
.
While charging, the unit may go into
Charger Back-off
protection
which automatically reduces the charge current to the batteries.
This is caused by:
1. The internal temperature is too hot – the charger automatically
reduces the charge rate to maintain temperature; or,
2. The AC input voltage falls < 85 VAC – the charger reduces the charge
current to zero to help stabilize the incoming AC voltage; or
3. FET Temperature.
