Hello, I updated my VM II 3K (24V) to firmware 43.28 and charging stopped. I need to roll back to U1 43.15. Does anyone have the hex file?"

Edited May 13May 13 by almusarrej

2 minutes ago, almusarrej said:

Hello, I updated my VM II 3K (24V) to firmware 43.28 and charging stopped. I need to roll back to U1 43.15. Does anyone have the hex file?"

1 hour ago, almusarrej said:

I updated my VM II 3K (24V) to firmware 43.28 and charging stopped. I need to roll back to U1 43.15.

Unfortunately, the 43.xx firmware version number range is a combination of VM II, VM III, and VM II premium firmwares, with VM II Premium firmwares starting at about 43.22 (possibly 43.20 was the first one). [ Edit: 43.22 or possibly 43.21 is the first in the 43.xx series to start using a different EEprom layout to versions 43.05-43.20. ] The 43.xx firmware series seem to have drifted from VM II (where the display is driven by the DSP) to VM III (where the display is external). My guess is that you've applied the VM II Premium firmware 43.28 to your early VM III non-Twin.

Alas, my 43.xx firmwares are a bit jumbled, so it will take me a while to sort them out. I don't have any 43.xx that is anywhere near 43.15 though. Are you sure that your inverter came with 43.15, and not say 41.15?

Edited July 15Jul 15 by Coulomb

Yeah, I'll get you a picture.

Having sorted out the mess that is the 43.xx firmware number range, I came across three newer (to me) 43.xx firmwares. The latest of these is 43.29, two days later than 43.28. Perhaps they noticed a whoopsie with the charging and updated the firmware quickly as a result.

This is main (U1) factory firmware version 43.29 for the Axpert VM II Premium 3kW and 2.5kW '28062 non-Twin. Do not use with any other model or version.

Use at your own risk. The hex file is dated 16/1/2025.

Firmware upload instructions for models with a removable display.

This firmware processes the QDOP command, so with suitably recent display firmware, it should support SoC% for settings 12,13, and 29 when connected to a suitable battery's BMS.

The rar file password is "flash" without the quotes.

VMII_Premium_2K5_3K_MAIN_Reflash_Ver43.29 pw flash.rar

Edited July 7Jul 7 by Coulomb

Thanks.. Thanks. I'll install and call you the result

Tryed but same problem with version 43.29 does not charge

I tried a second control with version 43.16 and the device was running normally from charging and operating

16 hours ago, almusarrej said:

Tried but same problem with version 43.29; does not charge.

OK, I'm now thinking that you want one of the firmwares in the range of 43.05 through 43.20 (inclusive, but possibly excluding 43.07 since it has a 3.6kW variant where the others have a 2kW variant). 43.20 was made only 5 months after your inverter was made, so it has the best chance to be compatible. Sorry for the delay in publishing this.

This is main (U1) factory firmware version 43.20 for the Axpert VM II Premium 3kW or 2.5kW '28062 non-Twin. Do not use with any other model or version.

Use at your own risk. The hex file is dated 13/09/2023.

Firmware upload instructions for models with a removable display.

This firmware processes the QDOP command, so with suitably recent display firmware, it should support SoC% for settings 12,13, and 29 when connected to a suitable battery's BMS. The RAR file password is "flash" without the quotes.

VMII_Premium_2K5_3K_MAIN_Reflash_Ver43.20 pw flash.rar

Just for completeness; I don't expect this to be any better for @almusarrej .

This is main (U1) factory firmware version 43.35 for the Axpert VM II Premium 3kW or 2.5kW '28062 non-Twin. Do not use with any other model or version.

Use at your own risk. The hex file is dated 24/08/2023. This firmware uses a different EEprom layout to firmware versions 43.0x and 43.20, but the same as versions 43.22 through 43.29.

Firmware upload instructions for models with a removable display.

This firmware processes the QDOP command, so with suitably recent display firmware, it should support SoC% for settings 12,13, and 29 when connected to a suitable battery's BMS. The RAR file password is "flash" without the quotes.

VMII_Premium_2K5_3K_MAIN_Reflash_Ver 43.35 pw flash.rar

I tried version I tried version 43.20 and version 43.35 and the same problem didn't work for battery charging

Hi Coulomb

,I hope you are doing well.I am following up on my previous posts regarding my inverter, the Voltronic Axpert VM II Premium 3kW (24V system).As you know, after I updated the firmware to Ver 43.28, the inverter completely stopped charging the batteries from both PV and Utility (the notorious zero-charging bug).I have carefully tried all the troubleshooting steps and workarounds you previously suggested in the forum (including isolating the system, battery-only cold restarts, trying different priority settings like SOL/SNU, and full factory resets), but unfortunately, none of them worked. The firmware remains glitched and refuses to initiate any charging current.My original stable firmware was U1 43.15, which worked perfectly before this update. Since this is a production system and my batteries are currently sitting empty, I am in desperate need of rolling back.Could you please check your archive or repository to see if you have the original Ver43.15.hex (or any stable, compatible 43.xx firmware for the VM II non-Max/non-VMIII) that I can flash to bring the charging functionality back to life?Your help is highly appreciated, as always.Best regards

10 hours ago, almusarrej said:

Since this is a production system and my batteries are currently sitting empty, I am in desperate need of rolling back.

Sorry, I can't help with rolling back, but I have sent a Private Message with two desperation messages to try.

I hope it worked; I got the endless spinning wheel after I sent it, and don't seem to be able to find sent messages to check it.

It didn't work, and I'm still waiting for the update file

12 hours ago, almusarrej said:

It didn't work,

Re-sent. It seems to have worked this time.

You're so helpful. I'm waiting for you