1 hour ago, Coulomb said:

I'm pretty confident that this will "fix" it, but of course, the proof of the pudding is in the eating

Patch 455.06 flashed...tomorrow by  this time I'll have a definite answer as to whether it has isolated the "never float" issue at least. 

1 hour ago, Coulomb said:

So it will have to wait till I get time to analyse it.

No worries....many thank for you zealous work and patience. 

Cheers

On 2023/02/27 at 4:48 PM, Coulomb said:

I'm pretty confident that this will "fix" it, but of course, the proof of the pudding is in the eating.

Sorry for not reporting back to you on this, had a big installation over the past 2+ days.

So about 3 days on this version, no errors, no warnings, no "never float" issue. To narrow things down, the current patch work on this version is not the culprit. Probably compatibility issue between the original code and whatever code is being inserted as premature float fix. 

On 2023/03/02 at 4:03 PM, mafiose13 said:

Probably compatibility issue between the original code and whatever code is being inserted as premature float fix. 

There is actually no "inserted code"; it's merely changing the sense of a branch instruction, effectively swapping the "then" and "else" clauses in a C statement; one of these fetches the float setting, one fetches the bulk/absorb/CV setting. The only thing affected by this change is the threshold for moving from absorb to float.

That's why I suspect that fixing this bug is exposing another. It would be good to swat this one. Maybe it will turn up in the King 1 firmware that Weber and I are fully patching and testing, though I really doubt it.

Finally Coulomb, have you succeeded in correcting the firmware for the transition to float? I read the five pages and I don't have the answer at the end! 

On 2023/02/09 at 3:44 PM, Mika said:

Hi!
I'm trying to connect the Axpert VMIII Twin 4K to the Felicitysolar LPBF2400-M lithium battery, but no luck... 

I tried everything and I'm almost sure that the problem is in the firmware...

So, I made the communication cable according to the instructions:
inverter 3 >> 5 (BMS port on Battery)
inverter 5 >> 6 (BMS port on battery)

And, I'm trying with all options/settings in Axpert's program 05: Pyl, Lib and Lic. It doesn't work with any option, it always gives error 61...
Further, I generally have a problem with communication with that model of Axpert...
Watchpower works fine with Axpert VP/VM 3KVA, also with VMIII-5000 48V, but won't with VMIII-Twin 4K. Neither via original RS-232 cable, nor via WiFi...
I even tried the USB connection from the PC. Does not work. Again Firmware...?

Maybe anyone can help me?

Solved with update Remote panel (v25.08) on the Axpert, plus update* BMS on LPBF.

Remote Panel_Reflash_MCU(25.08).rar

Hi,

Please can you share U2 19.16 FW for VM III 4KW ?
Thanks 

On 2024/08/29 at 8:03 PM, Khalil Koja said:

can you share U2 19.16 FW for VM III 4KW ?

That display firmware is available here.

There is also version 19.18 now; it's 13 months more recent.

This is factory display firmware for the Axpert King II (NOT original King 1 with 145 V  max PV) and Axpert VM III (4kW and 6kW) non-Twin. Do not use with any other model. The hex file is dated 23/11/2023. Use at your own risk.

Firmware upload instructions for models with a removable display.

Remote Panel_Reflash_MCU(19.18).rar

Edited November 24, 20241 yr by Coulomb

1 hour ago, Coulomb said:

That display firmware is available here.

There is also version 19.18 now; it's 13 months more recent.

This is factory display firmware for the Axpert King II (NOT original King 1 with 145 V  max PV) and Axpert VM III (4kW and 6kw) non-Twin. Do not use with any other model. The hex file is dated 23/11/2023. Use at your own risk.

Firmware upload instructions for models with a removable display.

Remote Panel_Reflash_MCU(19.18).rar 1.26 MB · 0 downloads

Thanks!
I really appreciate your efforts and helps.

Bonjour,

Je souhaiterais savoir si vous avez un firmware pour mon modèle d'onduleur Axpert VM III 6KW non-Twin.

Je suis actuellement avec le U1 55.71, mais qui ne me convient pas car lors du passage en mode EDF, EDF charge les batterie alors que moi je ne le souhait pas.

Et pour le U2 19.20.

Et si il y a des possibilités d'un meilleur rendement a l'ombre ou couvert matin et soir.

Le menu Max. AC Charging Current et 2A minimum.

Cordialement.

Merci d'avance.

This is main (U1) factory firmware version 55.11 for the Axpert VM III 1.5/4/6kW '28062 non-Twin. Do not use with any other model or version.

Use at your own risk. The hex file is dated 11/7/2025.

Firmware upload instructions for models with a removable display.

This firmware does not process the QDOP command, so it does not support SoC% for settings 12,13, and 29. It does not have the "presumed good" MPPT logic.

VMIII 4K_6K_DSP_5511.7z

Edited December 2, 2025Dec 2 by Coulomb

This is main (U1) factory firmware version 55.79 for the Axpert VM III 1.5/4/6kW '28062 non-Twin. Do not use with any other model or version.

Use at your own risk. The hex file is dated 08/10/2025.

Firmware upload instructions for models with a removable display.

This firmware does not process the QDOP command, so it does not support SoC% for settings 12,13, and 29. It does not have the "presumed good" MPPT logic.

VMIII 4K_6K_5579.7z

This is main (U1) factory firmware version 55.81 for the Axpert VM III 1.5/4/6kW '28062 non-Twin. Do not use with any other model or version.

Use at your own risk. The hex file is dated 18/11/2025.

Firmware upload instructions for models with a removable display.

This firmware does not process the QDOP command, so it does not support SoC% for settings 12,13, and 29. It does not have the "presumed good" MPPT logic.

Edit: The hex file has "TWIN" in the name, but it's definitely a non-Twin firmware, as are the other 55.xx VM III firmwares.

VMIII 4K_6K MAIN 5581.7z

Edited December 23, 2025Dec 23 by Coulomb

Is there any way to improve efficiency in shaded or overcast conditions, morning and evening?

Yes, by running suitably patched firmware. Georg594 pioneered this for the Axpert Max 8kW, I and a very few others continue it for other models.

Once you decide on a main firmware that suits your needs, I can patch it and post the patched firmware here. The patched firmware is not perfect, but my many accounts is vastly improved in low light conditions, and even some shading conditions.

For completeness, factory main firmware version 55.10 can be found here:

Thank you, on which version did you make these changes for improvement in low light conditions

On 2025/12/05 at 3:29 AM, Dim79 said:

 on which version did you make these changes for improvement in low light conditions?

I and others have made many patched firmwares for working around the "stuck at 90V" issue. See What Patched Axpert Firmware is That?

Edited December 8, 2025Dec 8 by Coulomb

On 2025/12/02 at 2:14 AM, Coulomb said:

This is main (U1) factory firmware version 55.81 for the Axpert VM III 1.5/4/6kW '28062 non-Twin. Do not use with any other model or version.

Use at your own risk. The hex file is dated 18/11/2025.

Firmware upload instructions for models with a removable display.

This firmware does not process the QDOP command, so it does not support SoC% for settings 12,13, and 29. It does not have the "presumed good" MPPT logic.

VMIII 4K_6K MAIN 5581.7z

So the 55.81 is the latest compatible U1 to VMIIIs 4kw (24v system), that replace the outdated 2 year old 455.06 (patched version of 55.06)?

On 2025/12/18 at 1:11 AM, mafiose13 said:

So the 55.81 is the latest compatible U1 to VMIIIs 4kw (24v system), that replace the outdated 2 year old 455.06 (patched version of 55.06)?

Yes, 55.81 is the latest firmware compatible with models that come with 55.xx, including 24 V models. But no, it does not fix the "stuck at 60 V" issue, as far as I know. If there is enough interest, I can patch 55.81.

Edit 23/12/2025: I assumed above that all VM III firmwares use a minimum MPPT voltage of 60V. In fact, some, including all the 55.xx firmwares, use 120V. Perhaps this is Voltronics' workaround for the "stuck at 60V" issue. But I don't believe that it's a complete fix.

Edited December 23, 2025Dec 23 by Coulomb

7 hours ago, Coulomb said:

Yes, 55.81 is the latest firmware compatible with models that come with 55.xx, including 24 V models. But no, it does not fix the "stuck at 60 V" issue, as far as I know. If there is enough interest, I can patch 55.81.

So 55.81 is unpatched, factory firmware!?

I have 4 units at my direct disposal that could use a fix of the "stuck at 60".

6 hours ago, mafiose13 said:

So 55.81 is unpatched, factory firmware!?

Yes.

6 hours ago, mafiose13 said:

I have 4 units at my direct disposal that could use a fix of the "stuck at 60".

Ok, these do seem to be popular models.

On 2025/12/22 at 6:12 AM, mafiose13 said:

I have 4 units at my direct disposal that could use a fix of the "stuck at 60".

As noted earlier, these 55.xx firmwares actually have the "stuck at 120V" issue, rather than "stuck at 60V" as I originally incorrectly posted.

But I believe that many owners will need the patched firmware anyway, as merely changing the minimum MPPT voltage is only part of the solution in general.

---

These are patched firmware versions x55.81, based on factory firmware version 55.81 for the Axpert VM III 6kW/4kW/1.5kW '28062 non-Twin. Do not use with any other model. The original hex file is dated 18/Nov/2025.

This firmware works around the "stuck at 120 V" problem by changing the current threshold from 0.50 A to 0.05 A. It also fixes the premature float bug, and changes the reported version number to x55.81. The removable display will continue to show version U1 55 81.

Use at your own risk; I cannot test this firmware as I do not own an Axpert VM III. It has been "sanity checked" by disassembling the firmware and confirming that the intended changes are present.

Choose the minimum MPPT voltage that is higher than your working panel voltage even in poor light.

dsp_155.81_patched.hex: Minimum MPPT voltage 100V. For very low panel voltage.

dsp_555.81_patched.hex: Minimum MPPT voltage 150V.

dsp_255.81_patched.hex: Minimum MPPT voltage 200V.

dsp_955.81_patched.hex: Minimum MPPT voltage 90V. For extremely low panel voltage.

Firmware upload instructions: https://forums.aeva.asn.au/viewtopic.php?p=87767#p87767

dsp x55.81_patched.zip

Edited December 23, 2025Dec 23 by Coulomb

On 2025/12/23 at 4:57 PM, Coulomb said:

As noted earlier, these 55.xx firmwares actually have the "stuck at 120V" issue, rather than "stuck at 60V" as I originally incorrectly posted.

But I believe that many owners will need the patched firmware anyway, as merely changing the minimum MPPT voltage is only part of the solution in general.

---

These are patched firmware versions x55.81, based on factory firmware version 55.81 for the Axpert VM III 6kW/4kW/1.5kW '28062 non-Twin. Do not use with any other model. The original hex file is dated 18/Nov/2025.

This firmware works around the "stuck at 120 V" problem by changing the current threshold from 0.50 A to 0.05 A. It also fixes the premature float bug, and changes the reported version number to x55.81. The removable display will continue to show version U1 55 81.

Use at your own risk; I cannot test this firmware as I do not own an Axpert VM III. It has been "sanity checked" by disassembling the firmware and confirming that the intended changes are present.

Choose the minimum MPPT voltage that is higher than your working panel voltage even in poor light.

dsp_155.81_patched.hex: Minimum MPPT voltage 100V. For very low panel voltage.

dsp_555.81_patched.hex: Minimum MPPT voltage 150V.

dsp_255.81_patched.hex: Minimum MPPT voltage 200V.

dsp_955.81_patched.hex: Minimum MPPT voltage 90V. For extremely low panel voltage.

Firmware upload instructions: https://forums.aeva.asn.au/viewtopic.php?p=87767#p87767

dsp x55.81_patched.zip

Thank you Coulomb, flashed 2 units and running perfectly as far as I can tell. The other 2 units are a bit farther geographically from me, for now ill let them be as is since I am not getting any complaints from the users.