Coulomb

If it's stopping at different times, then any firmware update will fail the same. It's either the USB to RS-232 adapter, or the cable needs a resistor (see the files section, link in the post linked below), or it's slow opto couplers inside the inverter or its display. You could also try the USB drive via a USB On The Go cable. That bypasses the serial electronics. See the Firmware Upload Instructions for details.

I can certainly port cuba.cz's changes to 2708.07, or even make a 278.08. But first I'd want to know that the changes are safe under all conditions.

The 71.xx and 72.xx King 1 firmwares are for the 5kW models only. The 51.xx and 52.xx are for the 3kW Kings. Possibly 52.01 uses the same firmware source code as 72.01, but compiled for the 3kW model, just using slightly different #define statements.

Yes, it has not updated. The other way to update requires a Windows PC, a compatible USB to serial adapter, and the grey D9 to RJ-45 cable that should have come with your inverter.

No, just interested in firmware, and South Africa for some unknown reason uses a lot of inverters 🤔 Also, I inherited a Dutch surname, but born in Australia.

I don't know the King II models specifically, but they all use much the same main power supply circuit, and that does have basically battery positive at one end of the load/start switch. So yes, that's expected. Alas, this means that plugging that into the wrong place could cause damage.

What exact firmware did you try to update it to? Have you tried the techniques in If you think your inverter is bricked?

I think it's a UPS: https://www.rctzone.co.za/power-solutions/power-solutions/line-interactive-ups/rct-850vas

My understanding, without owning a Max model, is that this should work. This is based on me reading the firmware; as far as I know, "mks2.hex" is not mentioned in any Voltronic documentation. So this is pure theory. So far, I'm not aware of anyone saying "hey, this does not work". Please report your results, good or bad.

If you are successfully running 78.xx firmware then you have a '28066 DSP. I'm 99% sure that recent EASuns are genuine Voltronic models, largely if not completely made in the Voltronic factory. Back in 2021, it may have been a different story. Large genuine Voltronic reseller MPPSolar accused EASun and others of being clone makers, and warning prospective buyers not to buy them. That web page is still there, but perhaps no longer easily findable: https://www.mppsolar.com/v3/fake/ I have a theory that Voltronic actually sues some clone makers, or threatens them with legal action unless they convert to becoming a genuine reseller. That appears to have happened with EASun and possibly a few others. In any case, I regard all EASun firmwares as genuine now, and as far as I know, they are completely compatible and interchangeable.

Answered in your other post here.

Please post in English on this forum. The needed cable wiring depends on the inverter as well as the battery. They probably provided a cable to suit a Deye or other common inverter. To fix that, we need to know the pinout at the battery end, or if the Pylontech compatibility includes the communications connector. There are usually several RJ-45 connectors on the battery, most of them 8-pin, so you also have to plug into the correct one. Hopefully you got a user manual with the battery, or at least there is a web site to download it from. Also, your display firmware, which handles communication with the battery's BMS, is fairly old. It might be worth updating it to version 12.28 or 12.29. Edit: They drop the leading "1" digit with recent display firmware, so recent 12.xx are compatible with older 112.xx display firmwares.

Yes, I can't see why not.

Please post in English on this forum. I don't have 82.07, but there is 82.06 in this thead; don't bother downloading the tmp (temporary) files, as these are automatically generated. https://powerforum.co.za/topic/24190-new-firmware-for-axpert-max-ii-10kw/#findComment-187125 I actually doubt that the differences between 82.02 and 82.07 would prevent paralleling; it's probably some other issue (e.g. cabling). What fault code comes up when you try to parallel? Edit: If you have trouble with the "stuck at 90 V" issue, you are probably better off updating both inverters to firmware version 82.63, which has the "presumed good" MPPT logic, and is 6 months later than 82.06. For whatever reason, 10 kW firmwares are more rare than others.

I assume you mean that the display that replaced the one that failed has version 38.08. I believe that you have an Axpert Max E 11kW Duplex model, so you need a Duplex removable display firmware. The only one I have is version 62.03. As far as I know, all the displays are hardware compatible with each other, as long as they are both removable or both round/colour, and have the same number of buttons (some have 4 touch buttons, others have 6 physical buttons). So this should work, but I can't guarantee it. You will need a Windows computer and a USB to RS-232 cable, as well as the cable that came with your inverter. This is factory display (MCU) firmware version 62.03 for the Axpert Max Duplex models. Do not use with any other model or version, not even a Twin model. Use at your own risk. The hex file is dated 23/11/2023. Firmware upload instructions for models with a removable display. Remote Panel_Reflash_MCU(62.03).rar

I'm not aware of places to buy just the cables. As far as I know, the cables are just straight through, i.e. pin 1 to pin 1, pin 15 to pin 15 and so on. I do hear of the parallel boards failing at times; I had one of my own take out a transistor due to nearby lightning. If you don't do electronic repairs, it might be worth buying a whole kit anyway. One of the old boards might be still working, so you can keep it as a spare.

Someone mentioned derating; it seems that it can derate charging power for four reasons. The reasons were high internal temperature, high PV voltage, low utility voltage, and I forget the fourth one. I was shocked to see a manual extract indicating that if PV voltage is over 360V, the charge current would be derated to a maximum of 90A. I suspect that there would be a ramp based on PV voltage, not a sudden drop of 33% as implied. That gives me a promising avenue to continue searching, if and when I find the time.

I usually do. In this case, fault code 90 is designed to "catch out" clone makers use Voltronic firmware without paying for it. I don't want to help clone makers in any way, if at all possible. In this unusual case, no patching was required, just updating to the latest firmware.

This is a complex issue. I've put a few hours into it with no bug found yet that might cause this, but I have to move onto other things. Please remind me again if I forget to get back to this.

Do you mean that the firmware failed to update, or it updated and there is no change, or now the inverter appears to be "bricked"?

I have read of one reader that did this successfully on a higher power model. The 12 V models usually have exceptionally small main processors (8-bit, tiny flash space), so maybe they don't have enough flash space to accommodate this change. It's also possible that the 12 V Solar Charge Controllers have different processors on them, such that this change is not possible. But I'm guessing wildly. My experience is mainly with the 5 kVA and higher rated models.

That's a user manual, not a service manual. As for why a totally new inverter won't come on, that's different. I note that the Axpert circuit that they probably copied has a capacitor that needs to be charged before the start circuit will work, so if it doesn't charge when switched on, wait a few seconds with the switch off before trying again. It may be possible to bridge the power switch (really a load switch, at least on Axperts) contacts with a screwdriver. Be aware that one side of the switch is probably basically unfused battery positive, so don't short the contacts to anything else. That may help to rule in or out poor switch contacts.

The above is factory firmware version 43.28 for the Axpert VM II Premium non-Twin 24V, 3kW or 2.5kW.

The main power supply, especially the part that "bootstraps" it on, basically the part around the two transistors below from my traced schematic: This circuit is usually near the large square yellow banded "transformer", as in the middle of this photo: It could also be capacitors worn out in that power supply; see this post for typical replacements.

Do you mean failed to find a suitable firmware update file, or used the wrong one and apparently bricked it? [ Edit: I don't know where got the below idea from. King II display firmware seems to vary a lot. Best to keep to the same major version number (the first two digits) as what you have now. ] It's the same display firmware as older VM IIIs and King 1s, the 02.xx series. The latest I know of is available here; ignore the 72.05 King 1 main firmware: