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2. Installation and connection

Last modified by Admin on 2025/03/18 13:04

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 18 must be protected from mechanical particles (dust, dirt, large objects) and water. The BMS Logic 18 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 18 has a heat sink to dissipate the heat generated during the balancing of the cells. When used in enclosed enclosures, heat must be removed from the sink, otherwise it may damage the device.

Overall and mounting dimensions of the BMS Logic 18 are shown below.

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ParameterValue

Overall dimensions (length × width × height), mm

214 × 140 × 16 
Mounting dimensions (length × width), mm198 × 132
Mounting holesM4

Headers

The BMS Logic 18 is designed to measure temperature and voltage of 18 battery cells.

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Attention!
All headers are shown from the device side!

X1 – header for cells

Receptacle Housing: Molex 430252000. Terminals: Molex 43030

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PinNameDescription
1V-Minus of the cell stack
2C2Cell #2
3C4Cell #4
4C6Cell #6
5C8Cell #8
6C10Cell #10
7C12Cell #12
8C14Cell #14
9C16Cell #16
10C18Cell #18 (maximum potential of the cell stack)
11--
12C1Cell #1 (minimum potential with respect to V-)
13C3Cell #3
14C5Cell #5
15C7Cell #7
16C9Cell #9
17C11Cell #11
18C13Cell #13
19C15Cell #15
20C17Cell #17

X2 – header 1 for temperature sensors

Receptacle Housing: Molex 430251800. Terminals: Molex 43030

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PinNameDescription
1TEMPG9Ground of the thermistor #9
2TEMPG8Ground of the thermistor #8
3TEMPG7Ground of the thermistor #7
4TEMPG6Ground of the thermistor #6
5TEMPG5Ground of the thermistor #5
6TEMPG4Ground of the thermistor #4
7TEMPG3Ground of the thermistor #3
8TEMPG2Ground of the thermistor #2
9TEMPG1Ground of the thermistor #1
10TEMP9Signal from the thermistor #9
11TEMP8Signal from the thermistor #8
12TEMP7Signal from the thermistor #7
13TEMP6Signal from the thermistor #6
14TEMP5Signal from the thermistor #5
15TEMP4Signal from the thermistor #4
16TEMP3Signal from the thermistor #3
17TEMP2Signal from the thermistor #2
18TEMP1Signal from the thermistor #1

X3 – header 2 for temperature sensors

Receptacle Housing: Molex 430251800. Terminals: Molex 43030

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PinNameDescription
1TEMPG18Ground of the thermistor #18
2TEMPG17Ground of the thermistor #17
3TEMPG16Ground of the thermistor #16
4TEMPG15Ground of the thermistor #15
5TEMPG14Ground of the thermistor #14
6TEMPG13Ground of the thermistor #13
7TEMPG12Ground of the thermistor #12
8TEMPG11Ground of the thermistor #11
9TEMPG10Ground of the thermistor #10
10TEMP18Signal from the thermistor #18
11TEMP17Signal from the thermistor #17
12TEMP16Signal from the thermistor #16
13TEMP15Signal from the thermistor #15
14TEMP14Signal from the thermistor #14
15TEMP13Signal from the thermistor #13
16TEMP12Signal from the thermistor #12
17TEMP11Signal from the thermistor #11
18TEMP10Signal from the thermistor #10

X4, X5 – headers for communication with BMS Main

Receptacle Housing: Molex 430250400. Terminals: Molex 43030

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PinNameDescription
1RS485_ARS-485 line A for communication with the BMS Main
2RS485_BRS-485 line B for communication with the BMS Main
3+5VSupply voltage 5V
4GNDGround

Switches and Indicators

SWD1 – address switch

Switch numberDescription
1The first (the lowest) bit of the address. Position ON - bit is 1
2The second bit is the address. Position ON - bit is 1
3The third bit of the address. Position ON - bit is 1
4The fourth bit of the address. Position ON - bit is 1
5The fifth (the highest) bit of the address. Position ON - bit is 1

Note: There is no SWD1 switch in the recent revisions of the BMS Logic 18. The device address must be configured in the settings (see the section 3. Configuration).

SWD2 – RS-485 termination resistor switch

To connect the termination resistor between the RS485_A and RS485_B lines, switch SWD2 to the ON position.

Note: There is no SWD2 switch in the recent revisions of the BMS Logic 18. Connect a 120 Ohm termination resistor directly to the X5 connector between the lines RS485_A and RS485_B.

DS1 – mode indicator

StateDescription
BlinkingConnection 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 18 do the following steps:

  1. Connect the BMS Main to the first BMS Logic 18 (P15 -> X4);
  2. Connect the BMS Logic 18 to each other (X5 -> X4);
  3. Switch SWD2 on the last BMS Logic 18 to the ON position or connect a 120 Ohm termination resistor directly to the X5 connector of the last BMS Logic 18.

Recommendations:
1. The total cable length (the sum of the lengths of all cables) between the BMS Main and the last BMS Logic 18 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 18.

Begin the connection with the negative of the battery: the "V-" of the first BMS Logic 18 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 18 is connected to the C18 of the previous BMS Logic 18. If not all inputs of the cells are used, then the remaining inputs are connected to the cell with the most potential.

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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).

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