Coulomb

81.xx is for some Max II 8kW models. 54.xx is for other Max II 8kW models. 281.05 is a patched version of 81.05, so it's suitable for all Max II 8kW models that are running 81.xx. The "x" here stand for any digit 0-9, e.g. 81.08 or 81.61. No, these are all "main" or "DSP" firmwares. On the front panel, the display version numbers are displayed at the bottom with U2 before the 4 digits of the display firmware, e.g. "U2 22 12“ indicates display firmware version 22.12. There are two (occasionally three) firmwares in these inverters. The "MPPT stuck at 90V" issue concerns the main firmware, which is displayed on the front display (with appropriate presses of up or down buttons) with "U1" in front of the main firmware version number, e.g. "U1 81 05" indicating either factory firmware version 81.05, OR patched firmware version 281.05. You can only see the full 281.05 version number from monitoring software, like Solar Assistant. So if you can find and report your main (U1) firmware version, I can help more.

That's unusual behaviour. My guess is a weak power supply. An OG 7.2 is probably getting old by now, so my guess is that the power supply capacitors have dried out. Replacing the usual suspects may fix it. If you are not handy with electronics and can't find someone who is, try to get a board level repair (tens of dollars plus labour), otherwise they will likely replace the main board at nearly the price of a new inverter.

My notes say that 81.xx are for the Axpert Max II, as are 54.xx, but for different DSP chips. These can't be mixed. I haven't seen where you say what your existing main (U1) firmware is. My apologies if I missed it.

Can you check if inverter 3 is missing a capacitor across the PV inputs? MKS IVs are known to be sensitive to this, usually affecting the display, but it might conceivably trigger other issues. There is a small file in the downloads section with slightly more detail. Be aware of the safety issues if you take this on yourself. Big high voltage capacitors can cause nasty shocks and/or damage underwear. Edit: Since fault code 72 is to do with current sharing, it may be to do with the length and/or resistance of the AC-out cables. If these are significantly different (you mention a 1 metre difference), it could be worth lengthening the cables from inverter 1 to the joining point, so that the lengths are more even. It's also possible that the current sense circuit for inverter 3 (or others) has a bad capacitor that would normally smooth out noise, for example from the PV input cables.

It means comms error to the BMS of the battery. Near the end of the manual, in a different section to most of the other fault and warning codes. Long ago it was the case that Axperts only connect to Pylontechs via RS-485, despite the Pylontechs being able to talk both, and the Axperts are able to talk CAN bus to other battery types. I believe that this is still the case. Do you have a cable from the inverter to the Pylontech BMS? Is the battery type set to PYL?

This page may help, though it is years old now: Use the bottom (PIP-5048MK) diagram.

Does the displayed battery voltage, when the inverter is not charging and has light loads, agree withing 0.1 or perhaps 0.2 V of a trusted multimeter's reading at the battery terminals? It may be that the inverter firmware is reading the battery voltage as higher than it actually is, and so thinks that the battery is already full when it isn't. Calibrating the battery voltage readings may help if that is the case.

Can't you send it back as unfit for purpose? Unfortunately, the problem is likely to be shorted MOSFETs and blown gate driver parts, which is a pretty significant repair effort and cost. It looks like these might be Axpert MAX 11 kW clones, though with custom firmware to drive custom displays. If so, this page might allow you to get started on the repair, or at least find out if it is basically the Axpert circuit: https://forums.aeva.asn.au/viewtopic.php?t=6007 Look in the schematic section for BritishRacingGreen's Axpert schematics. I think I need a new word for "clone", where the copy is of most of the intellectual property of the original, but the appearance and outward operation is somewhat different (to try to avoid prosecution, I would guess). So perhaps "workalike", but it doesn't seem to capture the process.

If by "cycle" you mean restart the MPPT logic, the standard MPPT patches achieve roughly that. Have you tried patched firmware version 281.05? It depends on so many factors. But from various posts with many MPPT performance graphs, it seems that on the worst days, you can lose something like 80% of available power for something like half the day. That's rare of course. Most days you probably lose 5-10%, and on the best days basically nothing at all.

There is Patched firmware version 281.05 but it's a bit old. I should update it for 81.08 and several minimum MPPT voltages. Life has been busy this year. But indeed there are no 54.xx for the '2809 DSP. I do have 54.06 now, so I could patch that if there is interest.

Those capacitors seem to work hard, and often seem to fail with weird effects. I don't believe that they are 100 nF as shown on the schematic, I think that they are closer to 10μF (at least for 5kVA 48V models). So it might be worth replacing those with decent quality 50V parts, if you can find them in a suitable size. The other possibility is more gate driver parts, like the bipolar transistors.

It can't be that; as far as I know iGrid implies Infini (on-grid) and iSolar implies Axpert (off-grid). So all Infini firmwares would be G not S, but that doesn't seem to be the case.

Just use your computer's file explorer. On Windows, you single click on the file name below a file's icon and the name will highlight, and you can edit it. Just click away from the name to confirm the change. As to what name to change it to, use the same file extension (part after the final period/dot) as the infini file names have. Actually, I have both of these in my collection, and they are both called "dsp.hex" (without the quotes). So there is actually no need to rename. However, that means that the old reflash tool will be looking for dsp.hex in the same folder (directory) as the reflash tool itself (the .exe file). So make a copy of an Axpert reflash folder, rename the dsp.hex to something like dsp_axpert.hex (or simply delete it), and copy the dsp.hex from a Infini reflash folder to that new folder. Go to that new folder, and run the reflash tool from there. That should cause the Axpert reflash tool to read the infini dsp.hex file. Assuming that works, the control board is now running Infini firmware, so any later firmware updates should be done with an Infini reflash tool. Yes, use monitoring software to perform a "factory reset" of most of the parameters. Do let us know how it goes. I suspect that you may run into problems with calibration of measurements, and possibly with serial numbers, and other things related to the EEPROM contents.

Are you saying that each inverter's grid input has a residual current breaker in series with a classic breaker? Or is the classic breaker on the inverters' outputs (heading to the loads)? 16A seems marginal for an 8kW inverter, especially on the AC input, where you might have 8kW of loads plus several kilowatts of AC charging. That could explain the 16A RCDs breaking, and that might somehow cause the 63A breaker to trip. I'll grant you that this is a long shot. It might be worth replacing the bypass relays (contactors?) in one of the inverters to see if that helps. Perhaps just the neutral changeover relay, as that switches earth to the inverter's neutral output. If that is slow or arcing or stuck, it might cause current imbalances that trip the RCDs. Also check the earth and neutral wiring of the premesis carefully. Just a little neutral current carried by an earth wire somewhere will unbalance active and neutral currents and cause RCDs to trip. Edit: Also check for screws missing on the main boards near these bypass relays. The earth connection to the changeover neutral relay usually goes through a hex screw and its threaded standoff, via the metalwork to the inverter's earth terminal.

It's not "normal", but it is common on many Voltronic Axpert inverters with the high PV voltage rating, which is almost all of them these days. I have a big post about patched firnware, see the section on MPPT stuck at 90V. It tells you what patched firmwares are available for particular models. Voltronic do have several firmwares that do OK with this issue, but none of them seem to be "mainline" firmwares with version numbers like xx.yy where yy < 60. But it seems that Georg's original patches work best. I merely adapt his patches to many Axpert firmwares for many models. There does seem to be a way that the bug manifests towards the end of the day, though it often seems to be less noticeable there compared to mornings. As to why the bug is there at all, my guess is that these MPPT chargers run off PV power, so in the morning, it's important not to demand too much PV power, as you may "strangle" the weak PV power needed to run the charger's electronics. Power electronics running on marginal power supplies is not a good thing, so they have special code to prevent this. As the AI suggests, it seems over cautious the way it does this. I have to say it's somewhat flattering to have AI mentioning my forum name directly 😊. Now if we could somehow train it to point to my patched firmware post directly, that would be wonderful.

That's up to you. The fully patched firmware has a number of features. But if you happen not to use any of those, you could go to factory firmware, which is now much more recent. Without release notes, we don't know how significant the factory firmware changes are. Main firmware is usually called DSP. I can't recall if this is important or not, but doing it in that order probably doesn't hurt. Edit: Sorry for the late reply.

It looks identical perhaps. But is the transformer turns ratio the same? Do the various sensors use the exact same scale? Does the EEPROM layout match enough to be useful? Is the DSP chip the same? I suspect that the Infinis might use floating point instructions, meaning that a '2809 DSP would just crash. It's possible that it might work, but I think it would be very risky, and I don't recommend it. Certainly it would require using an Axpert reflash tool with an Infini hex file, and you may need to rename the hex file. To go back again, assuming that it doesn't immediately brick the inverter, you'd have to di the opposite; use an Infini reflash tool with a suitable Axpert hex file again renaming as needed. Immediately after each reflash, you would need to run a command to reset the settings to factory. Even then, most if not all of the calibrations could be wrong, so many of the measurements could be inaccurate. Finally, in most jurustrictions, running the inverter would be illegal, as the inverter would be capable of exporting non-trivial power to the grid, and the model would not be type approved and registered (I think). There are just so many ways that this could go wrong.

Err, won't you need to add a beefy relay, its associated coil driver, and some hefty cables? Did you mean 71.03? Though that will be for 4.0 kW of rated output, not 4.2 kW. 71.03 is available here.

Assuming that this is the 145 V max PV model, 5kW, then the latest factory main firmware is 72.05. The latest factory display firmware is 02.89 (again, only the 145 V max PV model). Firmware upload instructions for models with a removable display. The latest fully patched firmware pair is 72.00a and 02.83a.

That's the U3 version. I need the U1 version, i.e. the one starting with U1 and then 4 more digits. I assume you mean it's a file whose name ends with ".bin" and is binary (i.e. if you type its contents, it's gibberish). Are you able to use that file to reflash your firmware? Presumably it came with other files, including instructions.

I create many patches, for a wide variety of Voltronic inverter models. The most recent set is x78.10, which has the "stuck at 90V" issue worked around, and optionally also or only the 100 A charge current limit threshold changed from 360 V to 450 V. But it won't work for your inverters, which have the '2809 processor, and 78.10 is for the '28066 processor. The latest patched x64.xx firmware set is indeed x64.62, available here with instructions. Unfortunately, 64.62 (on which the x64.62 patched versions are based) is a month older than the 64.09 that you have now. There is also factory (not patched) firmware version 64.69, which is 2 months more recent than 64.09, but I have not patched it at present. Also unfortunately, x64.62 does not patch the 100 A charge limit threshold. This is a fairly recently discovered issue, so there are only a few patched firmwares that implement it. I don't know the JK BMSs. If they talk a protocol that the Voltronic inverters support (e.g. Pylontech etc), then you could use that battery type with the inverters. They would also have to talk to each other, to get the maximum charge current correct for two paralleled strings of cells. Otherwise, you'll have to choose the USEr battery type, and forgo the ability to protect individual cells going over- or under-voltage. If there is enough call for it, I could patch 64.69 the same as I did 78.10. That would be the latest firmware available in the 64.xx series, and would optionally change the 100A current limit PV voltage threshold.

This is patched firmware version x78.10, based on factory firmware version 78.10 for the Axpert Max E 11kW '28066 Twin. Do not use with any other model. The original hex file is dated 26/Jun/2025. This firmware works around the "stuck at 90 V" problem by changing the current threshold from 0.50 A to 0.10 A. It also fixes the premature float bug, and changes the reported version number to x78.10. The removable display will continue to show version U1 78 10. This firmware also optionally changes the PV voltage at which the charge current is limited to 100 A from 360 V to 450 V. In each case, the version with this change has the higher first digit. The version without this change has the lower first digit. Use at your own risk; I cannot test this firmware as I do not own an Axpert Max. It has been "sanity checked" by disassembling the firmware and confirming that the intended changes are present. Firmware upload instructions: https://forums.aeva.asn.au/viewtopic.php?p=87767#p87767 Choose the minimum MPPT voltage that is higher than your working panel voltage even in poor light. dsp_978.10_patched.inv: Minimum MPPT voltage 90V. For very low panel voltage. The 100A charge limit patch IS present. dsp_878.10_patched.inv: Minimum MPPT voltage 90V. For very low panel voltage. The 100A charge limit patch is NOT present. dsp_578.10_patched.inv: Minimum MPPT voltage 150V. The 100A charge limit patch IS present. dsp_178.10_patched.inv: Minimum MPPT voltage 150V. The 100A charge limit patch is NOT present. dsp_378.10_patched.inv: Minimum MPPT voltage 200V. The 100A charge limit patch IS present. dsp_278.10_patched.inv: Minimum MPPT voltage 200V. The 100A charge limit patch is NOT present. dsp x78.10 Max E 11kW '28066 Twin patched.zip

I forgot to mention that this could be because you are not using a USB to RS-232 converter cable, attaching to the D9 to RJ-45 cable that should come with the inverter (but some clones may not supply it). You can make your own; pinout here (don't connect +12V, just the other three wires). The communications port is NOT an ethernet port, even though it uses the same connector. See Firmware Upload Instructions. You could also connect via USB, or attempt to use a USB stick via a USB OTG cable. All in the above instructions.

I need to know the main (U1) firmware version. You can still read this even in fault mode, either from the front panel, or via monitoring software.

Agreed. As far as I know, no genuine Voltronic firmware outputs anything other than 000dd.dd where all 4 of the ds are digits. So this is custom, or more likely patched firmware (patched by the clone manufacturer, not anyone on this forum). So it's really hard to guess what Voltronic model they might have copied. Because it's PF0.8 (rated power is 0.8 x rated VA), it's likely not a recent VM II model. It could be using an 8-bit processor, or it could use a '28062 DSP. So sorry, I can't be of much help.