I am finishing the install of my house battery system and will begin testing the various charging and discharging use-cases, including the bow thruster.
I do not want the REC-BMS to shut down when it sees a high initial current discharge (in-rush) and running current of the bow thruster.
•Custom CALB 230 Batteries: 2 x 4P8S
•9M REC Master with 2 x Q REC BMS units
•3 x V.E. 230V 50HzMultiPlus-II (24/5000/120-50)
•Max 360A charge from MP-IIs
I looked up the elect. motor on the bow-thruster. It's rated at 14kW,
which equals
= 18.78hp(I)
14kw / 0.746
= 18.77hp(E)
14kw / 0.73549875
= 19.03hp(M)
I was indicating the current draw from memory, so it may be lower in reality. Or the current draw was higher due to volatge sag with the old AGM batteries.
My main question has to do with making sure that the REC-BMS does not shut down when during the in-rush (locked rotor)phase which will last approximatley 200ms but could reach 200-300% higher than operating current.
I am trying to parse and understand this section from the REC-BMS manual.
VICTRON GX-SUPPORTED BATTERY MANAGEMENT SYSTEM WITH MPPT REMOTE ENABLE REC Q BMS - Rev 2.9.0 January 2023 Firmware version 1Q-4000+
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Battery Pack’s Discharging Algorithm:
Calculated maximum discharging current is sent to the GX device by CAN communication in each measurement cycle.
When the BMS starts/recovers from the error or from Discharging SOC hysteresis, maximum allowed discharging current is set.
It is calculated as:
Discharge Coefficient DCHC x Battery Capacity CAPA x parallel strings.
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My settings: DCHC= 3.0 x CAPA=960 x parallel strings = 2
3.0 x 960 x 2 = 5,760
From the manula, If this value is higher than:
Maximum Discharging Current per device MAXD x Number of Inverter/Charger Devices SISN, maximum discharging current is decreased to this value.
REC example:
Discharge Coefficient DCHC x Battery Capacity CAPA = 1.5 1/h x 100Ah = 150 A Maximum Discharging Current per device MAXC x Number of Inverter/Charger devices SISN = 100 A x 2 = 200 A
Maximum discharging current is set to 150 A.
I keep setting MAXD=345 and the REC keeps resetting it to 100
And I set SISN = 12 which does not make sense.
