Axpert Vm Iii Firmware

This is a technical guide for updating the firmware on an Axpert VM III series inverter (also sold under brands like MPP Solar, Voltronic, Kodak, and Must).

Warning: Incorrect firmware can brick your inverter. Verify your exact model number (e.g., Axpert VM III 3kW, 5kW) and current firmware version before proceeding.

4. Known Issues & Troubleshooting

Precautions before updating

  1. Read official release notes and follow vendor instructions exactly.
  2. Ensure the firmware file is from the official vendor or authorized reseller.
  3. Confirm the firmware is for the exact model (Axpert VM III) and hardware revision.
  4. Backup current settings and record configuration (charging parameters, time settings, communication addresses).
  5. Keep batteries at safe charge levels and connect a stable power source during update.
  6. Avoid interrupting the update (power loss or disconnected cable) — this can brick the unit.
  7. If available, perform updates via recommended connection (USB/RS232/SD card) and using official tools.

Step 4: Step-by-Step Axpert VM III Firmware Update Procedure

Follow these steps precisely. An interruption during flashing can permanently brick the DSP.

  1. Prepare the Inverter:

    • Disconnect AC input (grid/generator) and AC output (loads).
    • Disconnect PV solar panels (open the DC isolator).
    • Keep the battery connected. The battery voltage should be above the low cut-off (e.g., >46V for a 48V system).

  2. Connect the Cable:

    • Plug the USB-RS232 cable into your PC.
    • Connect the RS232 end to the RS232 port on the Axpert VM III (usually next to the BMS port).

  3. Install Drivers:

    • Install the USB-to-serial driver (e.g., Prolific, FTDI). Verify in Windows Device Manager under "Ports (COM & LPT)." Note the COM port number (e.g., COM3).

  4. Run the ReFlash Tool:

    • Run as Administrator.
    • Select your COM port.
    • Set baud rate to 2400 (standard for Axpert VM III main firmware).
    • Click "Load File" and select your firmware .hex file.

  5. Start Flashing:

    • The inverter LCD should be on (backlight active).
    • Click "Update." The tool will display "Synchronizing..."
    • Do not touch anything. Do not close the laptop lid or disconnect the cable.

  6. Completion:

    • The update takes 2–4 minutes. The tool will display "Write OK."
    • The inverter may restart and beep.

  7. Post-Update Reset:

    • Power down the inverter completely (disconnect battery for 30 seconds).
    • Reconnect battery.
    • Reconfigure your settings (battery type, output priority, etc.) as a full reset may revert to defaults.

When to update firmware

4. Update Main Firmware (U1)

  1. Extract firmware zip → folder with Reflash.exe and .hex file.
  2. Run Reflash.exe as Administrator.
  3. Select COM port matching your cable.
  4. Press Start Download.
  5. Immediately power cycle the inverter (turn off AC input, battery, then turn battery back on – some models need a full reset).
  6. The display will show UPG... then progress (0% → 100%).
  7. Wait – do not interrupt (risk of brick). After success, inverter restarts automatically.

2. Gather Required Tools & Files

Do not use VM II or VM IV firmware on a VM III – DSP chip differs.

How to Recover from a Bricked Axpert VM III

A failed flash (e.g., power outage during update) leaves you with a dead inverter – no display, continuous beeping, or fault code 90. Recovery is possible but advanced:

  1. Bootloader mode: Short specific test points on the control board (requires schematic knowledge).
  2. Direct JTAG programming: Requires a JTAG programmer like an ST-Link or J-Link.
  3. Send to distributor: Most users without electronics repair skills should RMA the unit.

2. Methodology: Non-Invasive Firmware Extraction