© 2020 Sensata Technologies
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8.3.1 How the Battery Monitor (ME-BMK) Operates
The ME-BMK battery monitor uses a precision resistor known as a shunt
to measure current
fl
ow into and out of the battery. The shunt provides a
small voltage to the Sense Module that is proportional to the current
fl
ow.
When current starts
fl
owing into or out of the battery, the Sense Module
measures the current
fl
ow and determines the amount of current removed
from and returned to the battery. The amount of current (or AHrs) removed
or returned is displayed on the remote control as the
AH I/O
(AHrs In/
Out). The AH I/O number is compensated by a charging ef
fi
ciency value that
accounts for energy loses while charging, and is one of the factors used to
determine the battery’s State Of Charge (SOC).
The battery’s state of charge—which is the best indicator of the condition of
the batteries—is indicated on the
Batt SOC
display. This display will show that
the batteries are fully charged (i.e.,
Batt
SOC = 100%
) once the following
three conditions have been met:
1. The charging voltage has stabilized over a period of time.
2. The charging current has decreased to a low percentage of the amp-hour
capacity—normally less than 2%.
3. The AHrs that were removed from the battery are within 1% of fully being
returned.
After the batteries have reached 100% SOC and have discharged
≥
0.5% of
the battery capacity setting, the charge ef
fi
ciency value will be recalculated
and the AH I/O read-out will reset to the recalculated value.
Info:
Charging from a generator (non-inverter topology) adds some
concern about the cost of fuel. A balance should be considered
between the use of fuel and the need to charge your batteries to
100% SOC—to maintain the full service life of a battery. Batteries
discharged to 50% SOC and then normally recharged to 85-90% SOC
would be an ef
fi
cient compromise between fuel cost and battery life.
Trying to restore the last 10-15% of a full battery charge requires
a long time—typically several hours.
8.4
ME-RC METER Menu Items and Settings for BMK
Press the METER button on the ME-RC to access the different meters that
determine the status of the inverter/charger and battery system.
01 INV/CHG Meter
– This menu provides the DC voltage and current of the
inverter/charger when inverting or charging. These are
not
BMK readings.
02 BM: SOC
– This display is the best way to monitor the actual state of
the battery. The read only display shows the State Of Charge (SOC) for the
connected battery bank. The SOC represents the condition of the battery as
a percentage of the available capacity left in the battery. The range is 0% to
100%, where 100% represents a fully charged battery and 0% means the
battery is completely discharged.
8.3
Operating the BMK using the ME-RC
This section explains how the BMK battery monitor works, and how to use
the ME-RC50 remote control to obtain battery bank information. It also
covers the various LCD displays that are related to the battery monitor and
the status of the Sense Module’s LED indicator.
8.0 Using a BMK
