BMS Connecting & Function Explanation

Parallel Model Connecting

The JKBMS Smart BMS supports parallel connection of multiple battery packs. When connecting in parallel mode, each BMS unit is linked together via the Parallel Module, sharing the B+ and P- bus bars across all units for balanced load distribution.

for soft prallel connecting please check the artical below:

https://jkbms-ess.com/blogs/news/2x-bms-soft-parallel-connecting-via-p-link-module

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Port Interface Definition

① T Sensor Port (HY2.0-4P)

The temperature sensor port supports up to two NTC temperature sensors for monitoring battery pack temperature in real time.

  • Pin 1: The 1st T Sensor A pin
  • Pin 2: The 1st T Sensor B pin
  • Pin 3: The 3rd T Sensor A pin
  • Pin 4: The 2nd T Sensor B pin

② Alarm / Buzzer Port (A12534WF-2A)

Used to connect an external alarm or buzzer for fault notification.

  • GND: Alarm power −
  • VCC: Alarm power +

③ Parallel Port (A1254WF-3A)

Enables hardware parallel connection between multiple BMS units via the Parallel Module (sold separately).

  • P-status: Parallel module status signal
  • P-EN: Parallel Enable signal output — low level opens the module
  • GND: Signal GND

④ Display Port (A1254WF-6A)

Connects to the JKBMS LCD display (e.g., LCD4.3) for real-time battery status monitoring.

  • K−: Active signal −
  • K+: Active signal +
  • GND: Power −
  • B: LCD RS485 signal −
  • A: LCD RS485 signal +
  • VCC: LCD Power out

⑤ ACC Test Port (A12534WF-5A)

Used for charger detection and ACC (accessory) signal testing.

  • C_Detect−: Charger output 12V −
  • C_Detect+: Charger output 12V +
  • NC: No Connect
  • ACC−: ACC −
  • ACC+: ACC +

BMS Interface Definition

① CAN/485 Interface (A1254WF-4A)

This combined CAN and RS485 interface allows the BMS to communicate with inverters, solar charge controllers (e.g., Solar Assistant via Raspberry Pi), and other smart devices. Available on HC and HCRPB series models.

  • CAN_L: CAN signal −
  • CAN_H: CAN signal +
  • RS485_A: RS485 signal +
  • RS485_B: RS485 signal −

Note: Standard BMS models (Bluetooth + UART only) do not include this interface. RS485 and CAN communication require HC or HCRPB series.

② GPS Interface (1.25T-4PWT)

This port is labeled GPS on the board but functions as a UART interface for connecting the LCD display or other UART-compatible accessories. It is not compatible with RS485 devices or Solar Assistant.

  • GND: Power / Signal GND
  • RX: UART_RX 3.3V
  • TX: UART_TX 3.3V
  • VGPS: Power out, voltage approximately B+

Note: Do not use the GPS/UART port for RS485 communication. To connect Solar Assistant or Raspberry Pi, use the RS485 port on HC / HCRPB series models.

Additional Hardware

  • Heating Film: Optional external heating film can be connected via the T Sensor port on supported models. Prepare the heating film yourself.
  • T Sensor: Optional NTC temperature sensor.
  • Battery Total + (P+): Main positive terminal of the battery pack.
  • Parallel Module: External hardware module required for hard parallel connection between multiple BMS units (HCRPB series). Sold separately.

Version Comparison

Feature Standard HC HCRPB
Bluetooth ✅ ✅ ✅
UART ✅ ✅ ✅
CAN ❌ ✅ ✅
RS485 ❌ ❌ ✅
Heating ❌ ✅ ✅
Buzzer / Alarm ❌ ❌ ✅
Soft Parallel (PLINK Module) ❌ ✅ ✅
Hard Parallel (Parallel Module) ❌ ❌ ✅
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