Battery Management System

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Introduction to RR370FRD 12/24V battery management system.
A system should be:
Safe
Reliable. This one has been since 2004.
Efficient. Use little power to operate.
Affordable. You can make it your self.
“Simple”
Auto or manual operation.
Easy to repair. Common parts, easily available.
I intend to introduce the system progressively by the use of drawings, comments, and hints on features for the reader to discover.
In order to keep the drawings contiguous it will be better for the members of the forum wishing to discuss this thread, to do it on another thread.
The first drawing is about the 12/24Vconfiguration of the batteries. As it can be seen the configuration as four outputs and the value of the current available to load A2 is the value of the sum of the CB protecting A1 and A2. The same will apply to load B2 as the schematic progresses. It is interesting to note that if Start is used with B2, and the demand on B1 is greater than 40A, CB40A will trip, indicating that Start and B2 does not have anymore the capacity to start. It is also interesting to look at the behaviour of the diodes, knowing that they produce a voltage drop, and it is interesting to look at the protection of each battery.

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RR370FRD 12/24V battery management system
The second drawing is about the two 12V DC generators (Bosch BX 55A).
On the working system the boat AC generator engine runs them. If I had only one main engine, I would use that configuration but I have not tested it.
As it can be seen the generators are wired in series. Regulators must read the output of their own generators. GA12 (Generator bank A, 12V) has been modified to be above ground (negative isolated from ground). As I was doing the modification I decided to install a Prestolite adjustable regulator (auto-electricians throw them away when alternators burn out) and do some charge testing with different voltage regulator settings. The testing let me conclude that there was no advantage in raising the voltage past 14.4V for a 1 hour running time, and no advantage in raising the voltage above 14V for time above 1 hour. That 750W was required to produce 338 VA. That it will be an advantage to delay the paralleling of a battery to minimise stress on the drive train. My other findings concur with what I have read in this forum.

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it look like the pic are missing

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RR370FRD 12/24V battery management system
The third drawing shows the wiring of:
M24, a 24V, 40A, 960VA generator.
M12, a 12V, 55A, 660VA generator.
W1, a 24V, 60A, 1440VA capstan with is emergency kill switch and surge suppression diodes.
An array of shunts facilitating the monitoring of the installation.
A 225A manual by-pass switch that allows the paralleling of a third battery for the starting of the engines SM Start Main and SG Start Generator.
The batteries are located near to their heaviest respective load:
A1 and B1 close to W1.
Start between the two engines.
A2 and B2 the closest to Distribution Board 1, DB1.
It is to be noted that the correct unit for power VA is used in this case, 1A at 12V = 12VA, and is not equal in power to 1A at 24V = 24VA. It important in a dual voltage system to express amps in correlation with their voltage.

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RR370FRD 12/24V battery management system
Drawing 4 shows
All the CB’s installed in DB1.
A surge suppression diode
Notice that shunt B2 SH2 100A can be bypassed by a 225A switch, which is operated when start paralleling.

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RR370FRD 12/24V battery management system
Drawing 5 shows
CB’s and switches associated with DB2
Em radio and essential lights (right side, starboard) have 3 sources of supply.
All others load 2 sources of supply and the possibility to balance load between bank A & B.
It is important that devices that require more than one supply (ST4000) be supplied from the same bank.
BATtery ManaGeR supply.
That B1+ is also A1- and A2-

Pic note:
The CB’s are installed up side down to minimise tripping shock in rough weather.

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RR370FRD 12/24V battery management system
Drawing 6 shows:
The five LED dot graphs indicate the voltage of each battery and activate the diode bypass relays AA, BB, STA when an engine is running.
This is a common kit easily available from Dicko, which is where some one wishing to build a system like this should start, first experimenting with one kit. The value of the resistor in series with a LED is for the experimenter to calculate and adjust to the same level of brightness as the other LED’s and also to select a suitable relay which should be Printed Card Mounted.

The picture shows a normal operation.

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RR370FRD 12/24V battery management system
Drawing 7 shows:
The physical disposition of the LEDs and switches and their voltage value. The system requires only 8 LEDs per row. It is for the experimenter to find a suitable way of wiring 10 outputs into 8 LEDs. LEDs and switches 1 to 6 are spare. LEDs can be wired to indicate engine running, time switch on, etc.

Notes on the battery monitor:
The battery monitor is protected against voltage spikes by a 10-ohm resistor and a 16V zener diode. If a voltage of 16V or above was to be applied to the terminal, for example from a solar cell array in open circuit (19.01V, then the resistor may burn out and the experimenter will have to learn how to de-solder.
To protect from reverse polarity a diode should be connected the correct way to GND (negative -)
The two positive (ignition + and battery +) must be bridged (connected together).
If the monitor was to be used as a battery tester, then a line fuse should be added to the circuit.
Information on the LM3914 dot/bar display driver IC can be found on Google search

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RR370FRD 12/24V battery management system
Drawing 8 shows:
The logic associated with the battery management. It is to be noted that each relay has a latching contact. Once a relay has operated it is not any more the subject of fluctuation from the battery monitor.

The picture Solar1 shows the solar cells charging battery A2. The voltage is in excess of 13.8V. When the solar cells reach this level under normal operation I will switch it off manually. During full charge, (14.8 to 15.1V) the battery getting the full charge is isolated from the system. For maximum efficiency, no regulator is used on the supply of the 40W solar panel.

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RR370FRD 12/24V battery management system
The following pictures show:
Gen1: battery monitor at rest. (No charging)
Gen2: Generator ON A2 – B2 charging.
Gen3: Generator ON, A2 – B2 above 13.8V, 60 second Delay Timer timing.
Gen4: Generator ON, elapsed timing, all batteries on charge. Relay AA2, BB2, ST2 and timer relay G ON.

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RR370FRD 12/24V battery management system
The following pictures show:
Main1: Main running idle, no charging.
Main2: Main running idle. 24V DC generator manually switched ON (for display purpose). A1, B1 getting charged. To be noted: A2, B2 getting charged through their respective blocking diodes
Main3: Main brought up to charging speed. 12V DC generator ON. Relays AA2, BB2, ST2 and LEDs M ON.

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RR370FRD 12/24V battery management system
Drawing 9 shows:
The timer associated with the Generator control.
Because the Generator starts at 2200 rpm the use of a timer will delay the operation of the logic. It is for the experimenter to find which contact to use (NO or NC) and how many. The experimenter can also experiment with the DIL switches and replace Tantalum capacitors to create a longer time delay.

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RR370FRD 12/24V battery management system
Drawing 10 shows:
The PCB form of the logic associated with the Generator control.

The picture shows the 3 PCBs: Generator control logic, timer and battery management logic, all installed behind the Perkins Main Engine board.

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RR370FRD 12/24V battery management system
Drawing 11 shows:
The Generator control.
The control allows remote Start and Stop from the Galley and Wheelhouse, and the switching On and Off of the two DC generators GA12 and GB12.
The Generator will stop on High Temperature Alarm and also on Low Oil Pressure.
To restart the Generator, a reset of the generator control will be required by switching the power OFF once the low oil pressure alarm has operated.

Note:
Wiring diagrams are drawn with the power switched OFF. Once the power is applied to the generator control, relay OP and contacts OP1 and OP2 and other relay(s) will operate, and the control will come to stand-by mode.

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RR370FRD 12/24V battery management system
Drawings 12 & 13 show:
The Main engine control.
The control allows a remote Start from the Cockpit and Wheelhouse. On Sentinel, low oil pressure will bring the Oil Pressure Light into permanent mode and sound an alarm.
The Main engine wiring.