Installation Manual

© 2014 Magnum Energy, Inc.
Page 89
Using a BMK: Monitoring
To view the SOC display: Access the METER: 05B Battery SOC display. If the AH I/O reading
is below 000 (negative number) when the SOC display reads 99%, then increase the charge ef-
fi ciency setting. If you fi nd that the AH I/O reading is substantially above zero when the SOC
display reads 99%, then decrease the charge effi ciency setting.
• 05B AmpHour Size – This setting is used by the battery monitor to calculate the battery’s
SOC. The AH size represents the amount of energy the battery can deliver.
Default setting: 400 AH
Range: 200-2500 AH
Note: It is important that the AmpHour Size setting is correct or else the calculations used to
determine the battery’s SOC display will be inaccurate.
Where do I set the AmpHour Size setting? Select the setting based on the 20-hr AH capacity
of your battery bank. Refer to the battery manufacturer for the 20-hr AH capacity of your par-
ticular batteries.
How do I determine my Battery Amp-Hour capacity? The batteries should be a deep-cycle
type and rated either by AH or reserve capacity in minutes.
• Amp-hour (AH) capacity is a measurement of how many amps a battery can deliver for a
specifi ed length of time (usually 20 hours) until the voltage achieves 1.75 VDC/cell at 80°F.
• Reserve Capacity (RC) is a measure of how many minutes a battery can deliver a certain
amount of current (usually 25A) and maintain a voltage above 1.75 VDC/cell at 80°F. If us-
ing the Reserve Capacity (25A), the 20-hour AH capacity can be estimated by multiplying
‘minutes reserve capacity’ by 50%.
Note: For batteries in parallel strings – add the AHr capacity of each string (Ex.: three 250AH
batteries in parallel = 750 AH); for batteries in series – use the amp-hour capacity of one battery
(Ex.: three 250 AH batteries in series = 250 AH).
8.2 BMK Operation/Monitoring with the ME-ARC
This section explains how the ME-BMK (Battery Monitor kit) battery monitor works, and how to
use the ME-ARC 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.
8.2.1 How does the BMK Battery Monitor Operate?
The ME-BMK 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 BMK sense module that is proportional
to the current fl ow. When the battery current starts fl owing, the sense module measures the
amount of current removed from and returned to the battery. The amount of current (or AH)
removed or returned is displayed as the METER: 05E AH In/Out value. This AH In/Out value is
compensated by the SETUP: 05A Charging Effi 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 METER: 05B Battery SOC display. This display shows that the batteries are fully
charged (i.e., SOC = 100%) once the following three conditions have been met:
1. The charging voltage has stabilized over a period of time (see Figure 8-1).
2. The charging current has decreased to a low % of the AHr capacity—normally less than 2%.
3. The AH that were removed from the battery are within 1% of fully being returned.
When the BMK sense module is fi rst connected, the batteries will need to be fully charged (i.e.,
SOC = 100%) at least once to establish a SOC reference point. While this reference point is being
calculated, the METER: 05B Battery SOC display shows “Think’n” to indicate that the SOC refer-
ence point is calculated. After the batteries are fully charged, the display changes from “Think’n”
to “100%” and begins to provide accurate SOC percentage values. After the batteries have
reached 100% SOC and have discharged ≥ 0.5% of the battery capacity setting, the charge ef-
fi ciency value is recalculated and the Amp Hours In/Out read-out resets to the recalculated value.
Info: To maintain the accuracy of the METER: 05B Battery SOC display and to keep the
batteries in good condition, charge the batteries to 100% occasionally (~ x1/week).