How-To: Connecting JK Inverter BMS to Victron

Integrating a JK BMS (specifically the PB-series Inverter BMS) with a Victron GX system (Cerbo GX, Ekrano, or Venus OS on Raspberry Pi) is the gold standard for DIY LiFePO4 builds. This setup enables DVCC (Distributed Voltage and Current Control), allowing the BMS to dictate exactly how much current the Victron MPPTs and Inverters should provide based on real-time cell data.

Step 1: Prepare the Hardware

To establish communication, you need a specific cable. Do not use a standard Ethernet cable; the pinouts are different.

  • Option A: Direct CAN Bus (Recommended) Use a Victron Type B RJ45 cable (or crimp your own).
    • JK End (CAN Port): Pin 4 (CAN-H), Pin 5 (CAN-L), Pin 6 (GND).
    • Victron End (BMS-Can): Pin 7 (CAN-H), Pin 8 (CAN-L), Pin 3 (GND).
  • Option B: RS485 to USB (Alternative) If your CAN ports are occupied, use a Waveshare Industrial USB-to-RS485 converter to connect the BMS RS485 port directly to a USB port on your GX device.

Step 2: Configure the JK BMS Settings

Before plugging it in, you must tell the JK BMS to “speak” the Victron language.

  1. Open the JK BMS App on your phone.
  2. Go to Settings > Inverter Protocol Selection.
  3. Select “Victron CAN” (often listed as Protocol #4).
  4. Ensure the BMS ID/Address is set to 1 (for the Master battery).
  5. Restart the BMS using the physical “RST” button or the app.

Step 3: GX Device Configuration

Once the cable is connected to the BMS-Can port on your Cerbo GX:

  1. Navigate to Settings > Services > BMS-Can Port.
  2. Set the CAN-bus speed to 500 kbit/s (this is the standard for JK and Victron).
  3. Go back to the main device list. You should now see “JK-BMS” appearing as a connected device.

Step 4: Enable DVCC (The Critical Step)

For the BMS to actually control the charging process, DVCC must be active.

  1. Go to Settings > DVCC.
  2. Switch DVCC to ON.
  3. Ensure “Limit Charge Current” and “Limit Managed Battery Voltage” are visible (they will be automatically populated by the JK BMS).
  4. Set Shared Voltage Sense (SVS) to OFF (the BMS provides this data).

Troubleshooting FAQ

Q: The BMS isn’t showing up on my GX device.

  • Check the Port: Ensure you are using the BMS-Can port, not the VE.Can port (unless you have changed the VE.Can speed to 500k).
  • Check the Cable: 90% of issues are cable-related. Verify your Pin 4/5 (JK) matches Pin 7/8 (Victron).

Q: I have multiple batteries in parallel. How do I connect them?

  • Connect the batteries together via their RS485-2 ports using standard RJ45 cables.
  • Set Battery 1 to Address 1, Battery 2 to Address 2, etc.
  • Only the Master (Address 1) connects to the Victron GX via the CAN port.

Q: Can I use the Bluetooth driver instead?

  • Yes, for older non-inverter JK BMS models, you can install the dbus-serialbattery driver on Venus OS to connect via Bluetooth, though a wired CAN connection is significantly more stable for 48V power systems.