Magnum Energy MMS-E Series User Manual

Page 32

3.0 Operation

3.1.2 Standby Mode

The MMS-E Series features an automatic transfer relay and an inter-
nal 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-E Series is equipped with an active

Power Factor Corrected (PFC) multi-stage battery charger. The PFC
feature controls 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 wave shape to mirror the voltage wave
shape). 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 Float 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 3-2). The Equalization stage (requires

the ME-RC50 remote)

stirs up stratiﬁ ed electrolyte and reverses 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 from 150-190 VAC – the charger reduces
the charge current to zero to stabilize the incoming AC voltage; or,

3. FET Temperature.