Coulomb

Those phase chopping dimmers are evil in mu opinion. I'm not surprised they upset many inverters.

Ah! Boy am I learning a lot today. So Triple A must be one of those resellers (like EASun and several others I believe) that rebrand Voltronic but also Must or other clone/workalike products. That QR code says "Originally manufactured by Voltronic Power". At last, a way of telling that an inverter is genuine! I've noticed those orange removable displays years ago. But I foolishly assumed that it was just an artistic thing to "go with" the orange blob on top. Sigh. Now I'll have to figure out how one of those buttons does up and down at the same time (at least, that's what it suggests to me). Thanks for the lesson!

Ah! Do they look like this? I can't tell from the photo if those are switch buttons or touch buttons. I note that Must inverters are not made by Voltronic, and often have non-Voltronic firmware (e.g. setting numbers different to that of Axpert, yet mostly do the same thing).

I've not heard of these. Oh! That's news to me. Just a description and perhaps a photo of these touch buttons, please. Now the multiplicity of display firmware versions is starting to make a little sense. I assume that all models with the round/colour display have touch buttons; is that correct? Thanks in advance!

Ah! That explains the 25 mm² wire to the resistors as well! Oh! So that's your only neutral to earth bond. So yes, don't attempt to undo that bond. It will disconnect if you have a suitable AC-in source. So if you ever do get a generator, or borrow one or whatever, make sure that it has neutral connected to earth, as this will be your only neutral to earth bond when AC-in powers the loads.

Ah! I thought ALL VM IIIs (old type and new type) have the removable display. * Does this VM III with the touch keys have a round (colour) display? * Is it branded Kodak? I am also very confused by the above (i.e. that 57.07 → 25.08 works for the VM III). Assuming that the 57.07 is a round (colour) display firmware, as I've just realised the 52.07 is. Is it possible that you confused 52.07 and 57.07 somewhere? It's a long shot.

I do however have 52.07 for King II Twin and others, and usually King 1 goes with VM III old, and King II goes with VM III new. Did I mention that these major firmware version numbers are confusing? So I find that 52.07 uses different GPIO pins to 25.12, or more accurately the same pins but in a different order. [ Edit: I now realise that 52.07 is for a Kodak OG-PLUS 6.2, which has a round display, yet it's a King II Twin. It seems that only Kodak Kings IIs (and possibly only the Twins of these) have the round display. ] There is a slight chance that the keys are still working, just jumbled up. So maybe the escape key is now the down key, or similar. Worth a try? If so, the solution might be tiny stickers over the key names 🤪

That might be the difference between 57.xx display firmware and 25.xx firmware: the way that the buttons are scanned. That seems crazy to me, but what do I know. Unfortunately, I don't have any 57.xx firmware to check, or for you to revert back to. Presumably, you can still use the inverter with monitoring software?

My experience is that they are usually wildly inaccurate like that, but sometimes much more reasonable, probably correct. But I could never figure out what the pattern was. So I assume it's something to do with the 72.00 firmware.

That seems OK, but I don't understand what the resistors across the battery busbars are for. That will cause almost 2 A continuous drain from the battery. Maybe these are meant to be pre-charge resistors? If so, they are not wired correctly (or your diagram is not correct). Yes. I would not. I assume that you have a generator for when you get days of poor solar weather; does your generator have a neutral-earth bond? If so, remove your existing bond. If not, consider leaving your existing bond there, and remove the screw near the double pole relay inside each inverter. That will remove the inverters' bond. You don't want two connections from neutral to earth, or you will have trouble with Residual Current Devices nuisance tripping intermittently.

I don't believe that these are Voltronic inverters: That control board doesn't look like any Voltronic control board I've ever seen. Also, per this video, fault code 03 is bus soft start fail; that's always code 09 for Voltronic. They do look quite Voltronic-like, apart from details like that. So I'd call these work-alikes (as opposed to clones or genuine models). Are the paralleling boards for Voltronic or for Felicity models? There may be subtle differences.

I've noticed strange solar figures from 72.00. I could not find the reason for it. There is a small chance that it's fixed in a later firmware, e.g. 72.05. I have not studied the differences. Beware of overlapping firmware version numbers with some Axpert Maxs.

So it's one of the two PF1 units (second or third models I listed). It's scandalous that they don't say whether it's a 58.4 V or 64 V model on the label. Yes. But again, which of the two models is it (i.e. is it the 64 V model or the 58.4 V model)? The other thing is what the age of the stock would be. I'm pretty certain that Voltronic have not manufactured this model for years. They won't age nearly as fast on the shelf, but they do age. Ah. I don't know whether Solar Assistant can change effectively two inverters at once. Maybe you can run two copies of Solar Assistant on two Raspberry Pis. If not "paralleled" (in three-phase mode), then they won't all change at once with just one command. But with suitable settings, the inverter should do it on its own. It may not change over at exactly the same time, but that should not be a big issue. Gathering data won't be as convenient if they are not "paralleled". As a point of interest, can you actually run the other two inverters now that the first one has stopped working? Or does it work well enough to still act as a master, even though it will be in fault mode all the time? Does it still charge the battery from its own solar? That's something that the high PV voltage models can't do. With these 145 V max models, the solar charge controller is quite independent. The faulty unit presumably can't charge from its AC-in. Yes, different firmware versions, even totally different models, does not matter if they are not being "paralleled".

Not easily. It might be easier to arrange an external fan, though the fans likely run backwards (sucking air down) so you might need one on each side. I highly doubt it. There are several posts about fault code 51 on the repairs and hardware modifications topic. The link is to the first post of the repair (fault code known) section, which has links to various posts, sorted by fault code. Most of these seem to involve capacitors. Yours is a clone (the fourth warning is a giveaway), so it may not even be possible to update the firmware. But a firmware update is unlikely to help in this case.

So these are 145 V max PV models? If so, they are going to be hard to replace, I'm afraid. First you have to know exactly what you have. I assume that they are MPPT models (max PV 145 V; the one you linked to is a PWM model with max PV 105 V). What is the main (U1) firmware version they are running? The next thing is, do you really need them to be running in three-phase configuration? That is, do you have any true three-phase loads? If not, and you can't repair that one, it might be best to run them independently, still sharing the same battery. It's not like they can share the loads, as you don't have any actually paralleled. This is a significant concern. Voltronic don't make it any easier, e.g. by telling you exactly what model it is, or even that it's made by Voltronic at all. You have to guess in many cases. If my guesses are right, you have to distinguish between three models: * 5 kVA PF0.8 (5 kVA but 4 kW) 58.4 V max battery voltage, 145 V max MPPT solar charge controller, running 72.xx (xx ≥ 40) or 73.00 * 5 kVA PF1 (5 kVA and 5 kW) 58.4 V max battery voltage, 145 V max MPPT solar charge controller, running 74.xx * 5 kVA PF1 (5 kVA and 5 kW) 64 V max battery voltage, 145 V max MPPT solar charge controller, running 72.xx (xx <= 40) If you happen to have firmware version 72.40, it could actually be either of the second two, and you have to check the maximum value for settings 26 or 27, so see if it stops at 58.4 V or continues on to 64.0 V. If you're asking can you repair them yourself, this may be a good option, but you obviously have to have a reasonable level of technical expertise and suitable tools. If you mean can you just physically remove the old model and replace it with a new, compatible model, then yes, as long as the firmware versions are very close (they don't have to be identical). I have most of those older firmware versions anyway, if you do want to match them exactly. If repairing, it sounds like it's the IGBTs that have failed. I would replace the battery-side capacitors as well, if possible on all three inverters, as a precaution. They are 6 years old now, which is about when the capacitors start drying out. If the battery-side capacitors fail, then that removes transient protection for the MOSFETs, so that's 16 MOSFETs and possibly also various gate driver components to replace. You really need a desoldering station to replace that many devices. It's also a good idea to replace the power supply capacitors, as these can cause various problems when they die; fortunately, when these die, they don't tend to blow up anything. It's such a shame that these inverters don't come with the option of paying 10% more and getting longer life / better specification parts. I guess it's something that is invisible from the outside, so people are loathed to pay more. I have two of these in parallel (the PF0.8 models), which have been running since 2016 or so. I did have to repair them both after a nearby lightning strike, and I did pre-emptively replace MOSFETs (no longer needed) and capacitors in both, when they were basically still new. One of them has had the power supply capacitors replaced as well. All the required repair information is in the repairs and hardware modifications topic. Good luck!

Hmmm. MPPT Solar is a known clone brand (hoping that people mistake it for the genuine MPPSolar brand). A genuine MPPSolar inverter will never say "Made in China", always "Designed in Taiwan". Yet the sticker looks legitimate to me. Is it branded "MPPT Solar"? If it's branded something else, then MPPT Solar inverter is a reasonable summary of what it does. The inverter with the short on the battery input: Does it smell of parts burning? Sometimes new inverters have a faint "hot resistor" whiff. If the MOSFETs have blown, you can sometimes see evidence of this by shining a torch into the holes in the cover on the right hand side, for example cracked MOSFET cases or legs blown off. Though the MAXs possibly use the larger transistor case, which may behave differently under severe overload.

I've just read too many posts from people blowing things up by plugging in a USB or RS-232 cable. I think in some cases, a portion of the load current returns through the earth wire of the USB port.

These firmware makers don't seem to practice any version controlling or standard software development methods. This means that firmware version numbers don't necessarily give correct clues as other standard software do. So, yes you can reflash different major versions of firmware. I would be extremely careful with this in general. The VM III and VM IV Twin models seem to be the messiest, with mostly 60.xx, some 76.xx, one 84.xx, and a 70.xx all apparently for the same hardware! With the main firmware for these models, all you have to check is that the firmware is written for VM III or VM IV, and that it's for a Twin model. These models all use the same '28062 DSP chip, so there is no incompatibility there. The VM III and VM IV displays are completely different, and so the display firmwares for these two models will always be different from each other. It's probably best to stick to 25.xx for VM III Twin display firmware, and 39.xx for VM IV Twin display firmware. Even though display firmwares version 57.xx appear to be VM III Twin compatible, and 63.xx appear to be VM IV Twin compatible. Edit: Be extra careful with 52.xx and 57.xx firmwares; see later posts in this thread. 52.07 is for a Kodak OG-PLUS 6.2, which seems to be an Axpert King II, but unlike all other Axpert King IIs that I know of, it has a round (colour) display!

Ah. Maybe that's because bucking 500 down to 50 V is very inefficient and/or difficult to control (small changes in the PWM ratio makes a large change in the battery current). But in an off-grid inverter, which already has a transformer based 500 V <-> 50 V converter, boosting from say 200 V (panel voltage) to 340 V or so (bus voltage) is fairly efficient (not such a wide voltage range). But maybe a transformer based solar charge controller would not be too expensive, I have no idea.

That's great to know, thanks. I wish you hadn't. The numbers yy.60 and above are not in date order; they're almost random. Fortunately, 60.95 is fairly recent (January 2024), though 60.87 is later (February 2024). 60.89 is earlier, December 2023. I don't have 60.08, but it's possibly later than 60.95 and possibly 60.87 as well. The 60.xx firmware date order is at the start of this useful thread: https://powerforum.co.za/topic/29708-axpert-firmware-collection-for-vm-iii-and-vm-iv-twin-models-only/ I've updated the post that the first post of that thread links to, which fortunately updates in that first post, even though I can't edit it. If that makes any sense 🤪.

Not in my experience. All the Axperts I've looked at common the digital ground with generated AC-out neutral. That should be at roughly ground potential, but may not. Yes, the power devices all have isolated gate drivers. But that's because their sources or emitters are high side or connected to BUS- or battery minus. The battery is isolated from everything, but the logic chips including the control board are not. The USB ports that are accessible from the outside are all isolated. Any internal USB port may not be isolated.

Wow, that's soon even if it's a clone. As far as I know, none are actually branded Voltronic, though some recent ones might (finally!) say that they are manufactured by Voltronic. I imagine that the cloners would be happy to copy that, though. If you post a photo of the sticker on the side, I can probably tell if it's genuine. Block out the last part of the serial number if you wish.

This is unfortunately not unheard of. Usually, some transient on the battery bus will cause one of the MOSFETs to fail shorted; when its opposite number turns on, there is a dead short across the battery, frying the second MOSFET (or set of 3-4 MOSFETs in parallel). The resultant current surge can often take out IGBTs as well, and also gate driver components as the gate melds with the source and drain. One common way that this happens is that the battery bypass capacitors (there are usually 4 of them) dry out with heat; they protect the MOSFETs from switching transients. are only rated for about 2000 hours at 105°C. If the inverter runs at 65°C, that's 4 x 10°C difference, meaning that the capacitors will typically last about 16x longer than that, or 32,000 hours. That's less than 4 years. Often the temperature will be lower, but problems can start occurring at around 5-6 years. How old is the unit that failed? Is it a well-known brand? Another possibility is that it's got even lower quality parts because it's a clone. They could fail in a much shorter time span. Or it could just be bad luck. A colleague of mine had an inverter explode its MOSFETs when operating a vacuum cleaner nearby. On examination, he found mysterious dark marks around the pins of the IGBTs. It seems that some sort of partially conducting material was there from the factory. When this was cleaned up and the IGBTs replaced, it worked well for years.

BE CAREFUL! It's possible that the USB port is only for diagnostics; it may not be isolated. Plugging it into a computer might cause large currents to flow and something may burn up. I would check for voltage between the 0V of the inverter and 0V of the computer before connecting them. If you see a solid voltage (check AC as well as DC), then don't connect them! Also, if this is a Must/Powmr/other clone, Watchpower likely won't recognise it. Having a menu item relating to RS-485 / modbus sounds very non-Axpert to me.

That doesn't sound right to me. Fault code 90 is all about the contents of the EPROM, which is on the control board, not any comms board. I can't see how it's possible to fry the comms board with that fault code. Is it possible that the tech is replacing the control board? I don't know what the insides of a Rack Mounted King look like. But replacing the control board also replaces the EEPROM chip, unless the Rack Mounted kings are vastly different. If he's replacing the control boards with clone control boards, then you will get another 60 days (around 2 months, not 4-6) from each control board, if running 24/7. If you are only running them 33-50% of each day on average, then that would give you the 4-6 months. What is your main (U1) firmware version? I may have it here, or one close to the same version, so I could PM you a patched version that prevents fault code 90 from ever coming up. Alas, rack mounted firmwares don't come up very often, so I may not be able to help.