Calvin

Hi @Coulomb, The answer is a combination of the overshoot and longevity. I only ran my setup in PYL mode for 10 days, when I first installed it (firmware 71.86 at the time). During this time I accumulated 86 SOH events over my 8 Pylons, and 3 complete system shutdowns. One of my Pylons was terminally damaged and replaced under warranty. They were all related to overcharging the Pylons. I changed to USR, 52.4V bulk, 52V float and built a micro-controller based system that communicates with the batteries and the inverters (a simplified ICC if you like). In the subsequent 6 months I have had zero shutdowns and zero SOH events. The batteries always get to 100%. It seems absolutely bizarre to me that the manufacturers of the inverter and the manufacturers of the batteries could collaborate to produce a "solution" that so effectively cripples/damages their own product. The forums are full of excellent posts explaining why 53.2V is simply too high. Can they not read / do they not care / do they not even test their own "solutions"? I am gobsmacked. They have done all the difficult bits, and then they screw it all up by using the wrong voltages? (Apologies for the rant, but I get sooo frustrated...)

One thing that is (almost) fixed is that the inverter no longer charges at 2A (per inverter) from utility when set to UDC (Utility Don't Charge) in setting 16. When in Line mode and no PV is available it now correctly sends no charge to the battery. It is still not quite right when blending PV and Utility: it still charges about 3-4A (in a 3-in-parallel setup), irrespective of settings. Biggest disappointments: 1 Settings 12 & 13 still make no provision for being percentage based when running in PYL mode. 2. Still no way to override the ridiculously high Charge and Float voltages the the inverter uses when in PYL mode. So, unless you don't mind overcharging your Pylons the PYL mode is still unusable.

I have just upgraded from 71.90 to 71.92 and I can confirm that 71.92 finally fixes the issue of the 2A continuous charge in line mode even when setting 16 is "UDC". I got the 71.92 files from Mustek.

Hi @Coulomb, any progress on this? I am looking at buying an Axpert to use as a mains charger and really want to use your Dynamic Charge Control. If there is no patch yet for this model, is there another model (available in South Africa) that you would recommend? (Thanks for all the great work)

@RichieRichLooking at the Pylon communications protocols, I do not see anything that looks like it can send a Charge voltage number to the inverter. I suspect that the 53.2V is hard-coded into the Axpert firmware. Remember, the PYL setting is specifically for the Pylontech batteries. It would be nice if Axpert made that a variable parameter. But then. they have no history of doing things that would seem obvious to me......

The King and the Pylon communicate fine at an electronic level, BUT: a. For some weird reason they use 53.2V, which, as you have seen, is way too high and causes all sorts of issues. b. If you use the Kings in parallel (as I do) it does not work at all. So, at this time (firmware 71.86) the only practical way of running them together is as you are now doing. The downside of this is that you do not get good SOC information. This can be obtained by interrogating the batteries directly using ICC or similar, or any device that can communicate via RS232. I have developed my own system using an Arduino. This an the additional advantage of allowing one to get around the well known PYLON issue with SOC values above 89%. I implemented a self-calibrating Coulomb counter to give accurate SOC all the way up and down the scale.

Not sure what happened here - both @Coulomband I suggested doing exactly this on 1 April. You read it and replied.....

@Coulomb, fair enough so they don't all write prefect English. The context of the original comment by @Gnome was that their English is not good enough to be aware of the work that you are doing. To achieve that they need only one engineer or developer who can read English.

I think @Gnome is being incredibly generous. First prize is that you hire competent programmers, and test and fix your software before releasing it. If/when you provide updates, you document the changes. Second prize is that you release software full of bugs, and have your customers test it for you. You then fix the problems, and provide well-documented updates to your customers. (Microsoft?) Last prize is to release buggy software, ignore all feedback, deny all bugs, and release new updates only to those who buy new hardware. You never provide release information. This is Axpert. As far as I am concerned the "they don't' understand English" argument does not wash. If you look at the contents of ".out" files provided with eg 71.86 you will see that variable and routine names are in very correct English - I would guess that their developers are completely proficient in English. Anyway, it is not an excuse. Their Chinese customers are experiencing the same bugs. The "they don't consider it a bug" argument also does not wash. Many of the bugs, and how to demonstrate them, have been extensively documented in these pages. The King inverters are close to dysfunctional - I remember reading @Coulombsaying a few months back that he would not recommend buying the King until the firmware is fixed. Even now the Kings simply do not work when used in parallel mode with Pylon batteries. They market the King as suitable for "mission-critical loads such as servers and ATMs" - they are surely joking. Their hardware represents excellent value for money. Their software is a disgrace.

I have had the same problem with these my Kings - as @Coulomb suggests it was an individual cell going over-voltage, causing an error 69 (stop charging) and sometimes a battery shut down. I have gone back to USR on battery type and 52.9V & 52.5V as settings 26 & 27 - it works beautifully. As an aside, battery type PYL does not work at all in paralleled Kings on 71.86 firmware.

Update: I found this (from the July 2019 version of the King manual) "If battery status is not allowed to charge after the communication between the inverter and battery is successful, it will show code 69 to stop charging battery." It seems consistent with the high cell voltage errors that I got.

Error 69 appears to be a generic error message that the King displays whenever the Pylon BMS reports an error to it. I had the same error when expanding my stack from 2 to 8 US3000s. Turned out to be a dud battery - the BatteryView software showed multiple cell over-and-under voltage errors on this battery. Had it swopped out - problem solved.

@Watt_The_F I recently went through the same process, also modifying the cable that came with the cable pack. The connection that worked for me is: Inverter <-> Pylontech US3000 Pin 3 <-> Pin 8 Pin 5 <-> Pin 7 No other connections needed. Hope this helps

I have now extensively tested 3 Kings in parallel (single phase) and it is clear that they simply do not work with the battery set to PYLON. The Master works fine, but the slave work correctly only until comms with the Pylon starts. After that PV input is frozen, all Query results (QPIGS, Q1, QPGSx) are frozen, it takes a hard reboot (disconnect utility, PV and battery) to get it going again. Once started the slave only runs correctly until the battery icon on the inverter connected to the Pylon starts flashing. The deal killer is the fact that PV input is only picked up on boot. Once the sun sets the inverter does not see any PV input the next morning without a hard reboot. I have tested it with different inverters (all on 71.86), different configuration parameters, always the same. For now I have reverted to battery type USER. Perhaps a future firmware update will fix it.... The good news is that, on USER, it works fine. No freezes, glitches, strange behaviours (so far...)

Sadly, it appears that it is not resolved. I have 3 Kings running in parallel on 71.86 and I can confirm that all the issues @Wilfred raised are still there. Only the inverter connected to the battery has correct SOC information - the others give endless Low Battery warnings. By synchronising the setup parameters (29) but not the SOC the developers have managed to make the system almost unusable. It seems that one either has to disable the beeper and live with endless Low Battery alarms, or go back to USE setting for battery type (or un-parallel the system - they seem fine in single-mode) @Coulomb, any chance of you and @weber doing a further patch on 71.80 (or 71.86) to resolve this issue? I assume that it is not present in the MS series?

OK, I have managed to fix it. Essentially, the USB OTG firmware update still worked, exactly as described in the manual. 1. Copy dsp.hex to FAT32 formatted USB. 2. Connect with OTG cable to USB port. 3. Start USB menu by holding down top left button for 3 secs. 4. Select Upgrade firmware, confirm, when it says "UPG YES" it takes about 10 minutes. All 3 now on 71.86😀 Update Jan 2024: It can take a lot longer. I started an upgrade (to @Coulomb's 72.00a patched) and after 30 minutes (of no progress/feedback/reboot) I was about to panic and power cycle when my wife called me for lunch. After lunch inverter had restarted and all was fine! Update Sep 2024: After step 3 above the screen may be blank. Press top left button again - it comes on!

@Coulomb I am afraid not. After power cycle it now has the 32 fault code on screen (nothing else). The fans run at 100%. No button seem to work, and the updater says "Failed to open comms 1" (The serial adapter and cable is fine - I can communicate with the other units.) I have swapped the comms/display unit with one from another inverter and it makes no difference - the fault is in the inverter itself. One minor point: the power button seems to work. (Press when off: unit powers on. Press when on (fans running): unit does not switch off, but after reboot it is off.) Not sure if there is anything to do? I can return it to Mecer I guess - surely they will be able to reflash the board directly? I had to attempt the firmware update as the 3 units I got from them did not all have the same version (1 x 71.50, 2 x 71.80). Parallel operation requires all 3 to have the same version. Any assistance / advice much appreciated.

Hi @MJS I just got 3 of these inverters. I flashed two of them to 71.86 no problem. Third stopped at about 10% with error 32. You say "I managed to get the communication going" - how did you do that? Mine simply goes to blank screen with "32" as soon as the boot count down is complete. Power cycle does not help.

Is that true even for the King? It is understandable for the others (fast transfer times) but the King runs off inverted DC all the time as I understand (zero transfer time)

Hi All, I am looking to go "off-grid" and am considering a system consisting of 36 x 330W Canadian Solar 3 x Axpert 5kVA inverters in parallel single phase mode 8 x Pylontech 3.5 kWh batteries (may be expanded later) 1 x 5 kW MAC-AFRICA 6.5 kVA Standby Silent Diesel Generator 220 V (for the no-sunshine days) The bit that I most need help on is the Axpert inverters. Specifically: 1. When connected in parallel, do they really act as a single unit: Are all PV panel outputs connected together, or is a third connected to each inverter? Are all the loads connected together, or is one third connected to each inverter? If one inverter fails, do they all go down? Should my generator be connected to only one unit, or to all three? (I will manage loads when the generator is the only input in order to not overload it) 2. I have read that these Axpert units are quite sensitive to the generator output (slew rates etc). Does anybody have experience with my proposed setup? 3. I have read various reports about the ability of the Axpert units to communicate with the Pylontech batteries. (Possibly due to older firmware versions). Anybody have a latest state of play? 4. I understand that the MKS II can run higher PV voltages (than the MKS or King), allowing one to have up to 9 (10?) panels in series. I want 12 panels so will need at least 2 strings and a combiner box per inverter anyway. Any thoughts on pros and cons? 5. Given that the MKS and King inverters specify MPPT voltage as 60-115, does that mean that one should have only 2 72 cell panels in a string when using those? (I see many people connect 3 due to max open circuit voltage of 145V) Any other thoughts / comments, particularly on choosing between MKS / MKS II / King would be welcome. Thank you in advance.