2. Installation and connection

Last modified by Admin on 2025/07/15 17:29

Installation and connection

Safety rules

Before use, configure the system. Proper operation of the BMS is possible only if it is correctly configured.

It is not recommended to use the system in batteries formed by several series of cells connected in parallel. To increase capacity, it is recommended to connect several cells in parallel groups, and then connect the groups in series.

Communication cable between BMS Main and BMS Logic devices must be deattached during connection of battery cells to BMS Logic. Connecting the battery cells while BMS Logic attached the the BMS Main may cause device damage!

The BMS can be connected to batteries with life-threatening and health-hazardous voltage levels. When working with high-voltage batteries, observe electrical safety regulations, use safety glasses, protective clothing, insulated tools and appliances. To prevent the damage of device avoid electrostatic discharges while working with the battery.

Installation procedure

The mounting area of the BMS Logic 12S must be protected from mechanical particles (dust, dirt, large objects) and water. The BMS Logic 12S is recommended to be placed close to the cells it controls, but away from high current circuits to reduce interference to measuring circuits and increase overall reliability of installation.

The installation site must provide convenient access for subsequent connection to the device’s headers.

The BMS Logic 12S has a heat sink to dissipate the heat generated during the balancing of the cells. When used in enclosed enclosures, heat must be dissipated from the sink, otherwise it may damage the device.

Overall and mounting dimensions of the BMS Logic 12S are shown below.

Parameter	Value
Overall dimensions (length × width × height), mm	117 × 62 × 16
Mounting dimensions (length × width), mm	106 × 52
Mounting holes	M4

Headers

The BMS Logic 12S is designed to measure temperature and voltage of 12 battery cells.

Attention!
All headers are shown from the device side!

X1 – header for cells and temperature sensors

Receptacle Housing: Hirose ZE05-24DS-HU/R. Terminals: Hirose ZE05-2022SCF

Pin	Name	Description
1	C1	Cell #1 (minimum potential with respect to V-)
2	C3	Cell #3
3	C6	Cell #6
4	C8	Cell #8
5	TEMPG1	Ground of the thermistor #1
6	TEMPG2	Ground of the thermistor #2
7	TEMPG4	Ground of the thermistor #4
8	TEMPG5	Ground of the thermistor #5
9	V-	Minus of the cell stack
10	C2	Cell #2
11	C4	Cell #4
12	C5	Cell #5
13	C7	Cell #7
14	C9	Cell #9
15	C10	Cell #10
16	C11	Cell #11
17	C12	Cell #12 (maximum potential of the cell stack)
18	-	-
19	TEMP1	Signal from the thermistor #1
20	TEMP2	Signal from the thermistor #2
21	TEMP3	Signal from the thermistor #3
22	TEMPG3	Ground of the thermistor #3
23	TEMP4	Signal from the thermistor #4
24	TEMP5	Signal from the thermistor #5

X2 – header for temperature sensors

Receptacle Housing: Hirose ZE05-16DS-HU/R. Terminals: Hirose ZE05-2022SCF

Pin	Name	Description
1	TEMPG6	Ground of the thermistor #6
2	TEMPG7	Ground of the thermistor #7
3	TEMPG8	Ground of the thermistor #8
4	TEMPG11	Ground of the thermistor #11
5	TEMPG12	Ground of the thermistor #12
6	-	-
7	TEMP6	Signal from the thermistor #6
8	TEMP7	Signal from the thermistor #7
9	TEMP8	Signal from the thermistor #8
10	TEMP9	Signal from the thermistor #9
11	TEMPG9	Ground of the thermistor #9
12	TEMPG10	Ground of the thermistor #10
13	TEMP10	Signal from the thermistor #10
14	TEMP11	Signal from the thermistor #11
15	TEMP12	Signal from the thermistor #12
16	-	-

X3, X4 – headers for communication with BMS Main

Receptacle Housing: Hirose ZE05-4S-HU/R. Terminals: Hirose ZE05-2022SCF

Pin	Name	Description
1	RS485_B	RS-485 line B for communication with the BMS Main
2	RS485_A	RS-485 line A for communication with the BMS Main
3	GND	Ground
4	+5V	Supply voltage 5V

Indicators

DS13 – mode indicator

State	Description
Blinking	Connection between the BMS Main and the device is established
Short flashing (~50 milliseconds in a second)	The device is measuring voltage and temperature. No communication between the BMS Main and the device
Long flashing (1 second in a 2 second period)	The device is in the bootloader mode

Connection procedure

Connection to BMS Main

To connect the BMS Main to BMS Logic 12S do the following steps:

Connect the BMS Main to the first BMS Logic 12S (P15 -> X3).
Connect the BMS Logic 12S to each other (X4 -> X3).
Connect a 120 Ohm termination resistor directly to the X4 connector of the last BMS Logic 12S.

Recommendations:
1. The total cable length (the sum of the lengths of all cables) between the BMS Main and the last BMS Logic 12S should not exceed 500 meters.
2. Make all connections with the same cable.
3. For a total cable length of more than 10 meters use twisted pair with the 120 Ohm wave impedance.

Connecting battery cells

To connect the battery cells, follow figure below. Incorrect connection of the cells can damage the BMS Logic 12S.

Begin the connection with the negative of the battery: the "V-" of the first BMS Logic 12S is connected to "B-", then the first cell (C1) of the battery is connected, then the second (C2), etc. The “V-“ of the next BMS Logic 12S is connected to the C12 of the previous BMS Logic 12S. If not all inputs of the cells are used, then the remaining inputs are connected to the cell with the highest potential.

Attention!
Connect the battery according to the diagram, otherwise the device may be damaged.

Connecting thermistors

Thermistors should be fastened to the cells, excluding short circuits to the cell terminals (for example, isolate thermistors with heat shrink). For reliable operation, it is recommended to use all thermistors (a temperature sensor per cell).