Hi, I've got a problem with an inverter that a can't solve after 2 weeks of reading and researching.   I have 2 Axpert Max 8kw inverters from Voltacon (genuine Voltronic I believe) that were installed in August this year.  They are in parallel, single phase, off grid, and charging lifepo4 batteries.  All was working fine until a couple of weeks ago when one morning I noticed the watchpower app showing a new device and my slave inverter offline. 

The slave inverter has a fault f11, PV over voltage, that shows on boot when the countdown reaches 2 and will do nothing.  I have disconnected all PV and battery connections and just feed with line in and the error remains.  The soft power button does nothing but I can still access menus for settings after boot and Watchpower still connects fine. The new device, my slave inverter, now has the default serial number 5535.......  So what has happened?  My logs show the battery ran out at 6pm ish (very dark skies) and there was no PV input.  The inverters were not set to bypass and the utility power was off to the inverters as I had already switched over manually to utility power via my transfer switch.  So my BMS would have disconnected power at 10% and inverter would have shut down.  When the sun came up the next day the new 'default serial' inverter awoke according to watchpower.  My PV voltages max out at 430v and the other inverter has never gone over this either and continues to run being fed by an identical array.  If i connect my pv array to the faulty inverter it reads the voltage pv input info correctly but doesn't charge or make ac.

The inverter is under warranty but Voltacon in the UK have been less than helpful, not answering my questions simply saying the pv is over voltage.  They are not sure they can repair if I return it and they don't seem to want to engage in conversation about what I suspect is faulty.  I want to see if there is a possible solution without returning the unit to Voltacon as if repair is unlikely replacement is also unlikely as stock is non existent here right now so could be a very long wait (it took 6 months originally).

Could it be that the power loss/reinstatement caused an eeprom fault resulting in the default serial and giving what I think is a red herring f11 error?  Is there a way to correct this with firmware?  I have tried resetting the serial with the AxpertSetSN tool but the inverter just returns the default serial, which is probably the real issue here.  The firmware on my inverters is 72.03 which I would have tried to flash already but it doesn't seem common or available.

If the inverter is toast than so be it and I'll have to return it but I'm hoping there might be a soft solution.  I'd also like to figure out what has happened to it so to avoid it happening again and save anyone else doing the same.  Thanks in advance.

5 hours ago, Tonypee said:

The new device, my slave inverter, now has the default serial number 5535.......  So what has happened? 

The serial number is stored in a tiny EEPROM device on the control board. It sounds like that became corrupt somehow, and has forgotten its legitimate serial number.

I think the best solution is a new control board from your supplier, Voltacon. Though they might be able to supply a "set serial" program set up for your slave's specific serial number.

The problem with either approach is that the EEPROM also contains some calibration constants, pertaining to hardware on your main board. I suspect that these should be set up with special equipment, usually done at the factory. So returning the whole unit might be best.

I also worry that you might end up with fault code F90 after 60 days of losing your serial number. The serial number is part of a complex calculation that determines whether or not the firmware is running in a clone or a genuine Voltronic. If it decides it's a clone, it delays F90 for 60 days, apparently to maximise inconvenience for the clone manufacturers and their end users. So that might be a reason to get this sorted with your supplier; don't let it drag on for months.

Thanks Coulomb.  I thought it might be terminal for me being able to fix it but having your opinion is good reassurance.  Have you seen this sort of eeprom corruption occur before?  I read somewhere that having parallel inverters can be problematic.

I suggested resetting the serial to Voltacon but it just got ignored.  I'll box it up and ship it off to them.  I'll update if and when I get feedback as to what has happened to the inverter.  Thanks again

4 hours ago, Tonypee said:

Have you seen this sort of eeprom corruption occur before?

Yes, it seems to be more common that you'd expect. Sad that a R10 chip can bring down a R10k inverter.

Voltacon have sprung into life and have requested flashing/serial files from Voltronic.  I was going to get it it boxed up but I'll hang on and see what they can do.

Voltacon contacted Voltronic who sent me the AxpertSetSN tool to try and resurrect my serial number.  Alas this didn't seem to work.  The tool reads back the default serial.  On second try it will read out my serial but it doesn't stay.  I reboot the inverter and default is back.  Not sure if I've done it right but tried every which way and it just doesn't work.

2 hours ago, Tonypee said:

On second try it will read out my serial but it doesn't stay.  I reboot the inverter and default is back. 

That sounds like a rare, but not unheard-of hardware fault. Since their approved technique failed, I think warranty repair or replacement is justified.

I wanted to update this thread as I have had some strange developments.  Voltacon took my inverter back, replaced the mppt input board but that didn't fix the issue.  They then replaced what they call the DSP/control board and that fixed things apparently.  Unfortunately the returned inverter had was reading 3-4a  input on mppt 2 constantly even with no input and was not functioning correctly. Otherwise it was fine so it may have been the replacement mppt board that was changed unnecessarily or even the control board as this was apparently taken from an 11kw unit they had.

Anyway, this took some time and I was eventually sent a new inverter which I setup in parallel with my other unit.  Everything was fine and I decided to add a Raspberry pi with solar assistant to my system to add a bit more monitoring and control.  After a few days I noticed the mppt voltage on the new inverter jumping up and down at night.  0v then 60v then 0v etc.  I did a little testing and this only occurs on a clear night with moonlight and I get anywhere between 3v and 10v at the mppt input from the panels.  This is enough to constantly tun the solar charge controller on and off, all night long.  With the inverter in standby mode it literally turns on and off all night long.  The input voltage is normal during the day, the mppt holds it at 90v as the sun sets and then shuts off.  A little while later, it wakes for the night time session!  The graph shows a typical night of the 2 inputs.  There's no current or power associated with this.  At the pv inputs with the panels disconnected I read 31.5v across the input terminals coming from the inverter.  I thought the SCC and mppt side of things should be shut down at low voltage input and there would be some sort of threshold for startup.  Further to this, the replacement inverter has again lost its serial number and reverted to 5535... 

This has not happened to my other inverter and the only difference in the setup between the two is the faulty one has panels at 35 degrees and the other at 60 degrees.  The lower angle catches the moonlight and outputs whole volts as opposed to mv on the steeper ones.

So, I have 2 questions.  Should there be 31.5v at the pv input?  This is there even if the battery is disconnected. 

Should there be threshold for scc startup and could the cycling of the inverter have caused damage/loss to the EEPROM or control board?

 

14 hours ago, Tonypee said:

They then replaced what they call the DSP/control board and that fixed things apparently.  Unfortunately the returned inverter had was reading 3-4a  input on mppt 2 constantly even with no input and was not functioning correctly. Otherwise it was fine so it may have been the replacement mppt board that was changed unnecessarily or even the control board as this was apparently taken from an 11kw unit they had.

Huh. So do you have 8 kW firmware now, or 11 kW firmware? What is your main (U1) firmware version now?

14 hours ago, Tonypee said:

I read 31.5v across the input terminals coming from the inverter. 

Someone else has reported 63 V measured at the PV inputs at night (by monitoring software I believe, not a multimeter).

The SCC for these high PV voltage models is basically a boost converter:

In this case, Vo is the bus voltage, and Vi is the PV input. S is a MOSFET, which would be open circuit at night. The diode should prevent reading any voltage at the input. Perhaps the diode is leaky.

14 hours ago, Tonypee said:

Should there be 31.5v at the pv input?

As far as I can tell, no.

Quote

This is there even if the battery is disconnected.

But is everything else disconnected, e.g. AC-in? If there is no bus voltage, I can't see where the voltage could come from. You can get weird effects from noise getting rectified, but that's always a few volts or less.

14 hours ago, Tonypee said:

Should there be threshold for scc startup

Yes.

14 hours ago, Tonypee said:

could the cycling of the inverter have caused damage/loss to the EEPROM or control board?

I find that very hard to believe. The EEPROM is located on the control board, so replacing the control board also replaced the EEPROM.

That's seriously weird.

Hi Coulomb. I'm back to having a brand new 8kw max inverter as they replaced the one that they failed to fix.  So I do have two identical inverters in parallel.  But this replacement has started failing in the same way as the last and I get the odd f11 fault since the serial number defaulted which goes away on restarting.  It's only been installed for a month or so.  It's from the same batch/shipment that came from Voltronic last year. Main firmware U1 is 72.03, display is 12.21.

It certainly seems like a voltage leak.  Funny thing is if I swap the PV inputs from the other inverter I get the same issue on that inverter.  It makes me think that there is possibly a fault with this batch of inverters.  It has only become apparent as I have an array that is good at catching moonlight.  Both inverters read the same 31.5v at the pv input with the battery disconnected.  To test that I have to power the inverter by ac in, but the same applies with the battery connected and no ac in (panels isolated obviously).  So I assume the voltage must be coming from the bus?

But only one inverter suffers and the only thing different between the two is the repeated cycling of the charge controller, night after night.  Perhaps, like most of us, the control board doesn't like being woken up every minute at night and has caused an issue?

I'm isolating my panels at night at the moment but I think it'll only be a matter of time before this ends in f11 misery.  I also have an Axpert King II 5kw that I can connect to this pv array and have none of these issues.  Goes to sleep at sunset and wakes in the morning perfectly.

 

 

3 hours ago, Tonypee said:

So I do have two identical inverters in parallel.  But this replacement has started failing in the same way as the last and I get the odd f11 fault since the serial number defaulted which goes away on restarting.

Ah. Reading the firmware, I see that the PV-too-high threshold is stored in RAM, and read at power-up from EEPROM. The fact that the problem goes away with a restart suggests that the EEPROM has the right value, but the RAM value is being over-written. That's every coder's worst nightmare: memory getting over-written by a wild pointer or some such.

It's possible that more RAM was being corrupted, and these corrupted values were written to the EEPROM in your original inverter. If so, your present inverters are "ticking time bombs". 

It's slightly possible that they've fixed this in 72.04, one minor revision higher than the 72.03 that you have now. I suggest it's worth a try:

 

Thanks Coulomb.  It certainly feels like a ticking time bomb.  I'm feel like tearing the inverters or my hair out.  I'll update the firmware and report back.

No joy with firmware.  I have made some progress with this voltage at the pv input terminals.  It occurred to me I was testing the voltage at the pv input referencing to each other, positive input and negative input.  I wasn't checking to ground (or neutral, which is combined for my system).  Panels isolated I read -150v dc to earth on the pv+ terminal and -192v dc on the pv-.  This is the same if the inverter is powered only from battery or only from grid input (or both).

Now here's the funny thing.  If I disconnect the inverter earth and isolate everything except the battery and put the inverter into 'standby' i.e. button not pushed in I would expect it to sleep.  It does, but then wakes, then goes off, then wakes ad infinitum.  Same cycling I see when I get a moonlit night with everything connected.  It doesn't do anything and nothing comes on the display to show charging, input or solar.

I questioned my setup but my pv input on the coldest brightest mornings only reaches 450 Voc and I've only ever got clipping of power a couple of times.  The 5KW inverter behaves fine in the same configuration.  Like you said Coulomb, this has to be voltage leak from the dc bus doesn't it?  I don't know if it was like that from the start or happened after installation and some use.

5 hours ago, Tonypee said:

Panels isolated I read -150v dc to earth on the pv+ terminal and -192v dc on the pv-. 

Yes, AC-out neutral (should be at earth potential) is alternately connected to BUS+ or BUS- 50 times per second. So BUS- (which is also PV in minus) will be at either approximately -385 V or 0V, so the average will be about -192 V. With no PV connected, PV+ should be about the same, but because of this fault, it's reading some 40 V higher.

5 hours ago, Tonypee said:

If I disconnect the inverter earth and isolate everything except the battery and put the inverter into 'standby' i.e. button not pushed in I would expect it to sleep.  It does, but then wakes, then goes off, then wakes ad infinitum.

When the switch is "off", it doesn't actually mean turn off completely, it means don't send output to the load. So it can still charge the battery from utility or solar with the switch "off". It's confusingly named. They should call it a "load switch" or "output switch" or similar. So the inverters have sense circuitry that tells them when PV is present; if so, it activates a special circuit to wake the main power supply, and the DSP is supposed to figure out that it can do solar charging now. But it seems that you have enough voltage present at the PV input (even with no panels) to trigger waking the main power supply (that's a pretty dumb circuit), but the DSP makes actual voltage measurements and correctly determines that there is no PV present. So after about 30 seconds, it decides that with no charging sources and the switch off, it should turn off the main power supply. The cycle thenrepeats.

5 hours ago, Tonypee said:

my pv input on the coldest brightest mornings only reaches 450 Voc

Is that the upper limit? Or is the upper limit 500 V, with 450 V being the maximum MPPT voltage?

Thank you for the explanation Coulomb, makes perfect sense.  You summarised exactly what I'm seeing.  I't nice to know what is going on so I can go back to the supplier and explain the situation. So the little bit of voltage I get from the panels at night, combined with the leaking voltage, is enough to wake the sense circuit.  But not on a cloudy night.  I never would have noticed this but for the fact I often have the second inverter running not in output mode and just as a charge controller.  In fact, it probably wouldn't have gone wrong. 

The Voc upper limit in the manual is 500v with an mppt working limit 450v.  The array was designed to not exceed 450v at -5 degrees, which it rarely gets to here, so Is withing spec.

So I know there is a leak that causes the cycling, but is the leak casing the serial number issue or is it the repeated cycling that then causes that problem?  Hmmm.  Either way it's not right.  I would have thought someone else would have had the same problem, but then again, there are other variables that need to met for it to manifest.

I have double checked my measurements at the terminals to earth with no pv connected.

PV+  -192.5vdc  193.5vac

PV-  -149vdc   194.1vac

Between the pv + and - 32.6vdc, I can't read ac as my DMM reading jumps all over the place

For a sort of reference, my good 5kw king II reads,

PV+  -1vdc  180vac

PV-  -124.5vdc   184.8vac

Between the pv + and - 50.06vdc, 4.74vac

15 hours ago, Tonypee said:

For a sort of reference, my good 5kw king II reads,

PV+  -1vdc  180vac

PV-  -124.5vdc   184.8vac

Between the pv + and - 50.06vdc, 4.74vac

Huh. This is with no PV connected, right? I'm surprised. The King II seems to have a higher leakage. Or maybe this is meaningless.

15 hours ago, Tonypee said:

I can't read ac as my DMM reading jumps all over the place

(for the MAX that is playing up). Interesting, I wonder what this is telling us.

I'll have a think about this and see if anything comes to mind.

Yes, all readings with no pv connected.  I wonder what the erratic readings from the DMM are too and suspect that could be where something strange is going on.  

I have re-checked my readings as something seemed off with my meter and have taken them again.  I hope they provide I better picture.

I also noticed something unusual while taking some frequency readings between earth and the pv input terminals.  On the 5kw nothing happened at all on + or - but with my 8kw Max when I probed the + input terminals (not the -) it triggered the scc, just like a moonlight night would.  The pv display showed 90-100v or so and went off.  I assume the frequency setting on the dmm has continuity through the meter between the probes and provided a circuit through to earth.  I am now speculating this is what happens when the solar panels get that little bit of light on a bright night and allow a lower resistance pathway through the array that is otherwise too high?

Max 8kw,

PV+  -147vdc  207vac

PV-  -187vdc   207vac

Between the pv + and - 33vdc, 0.7vac

For a sort of reference, my good 5kw king II reads,

PV+  -83vdc  199vac

PV-  -127vdc   204vac

Between the pv + and - 50vdc, 5vac

2 hours ago, Tonypee said:

I assume the frequency setting on the dmm has continuity through the meter between the probes and provided a circuit through to earth.

An extremely high resistance (low conductivity) path, yes.

2 hours ago, Tonypee said:

I am now speculating this is what happens when the solar panels get that little bit of light on a bright night and allow a lower resistance pathway through the array that is otherwise too high?

Moonlight should only affect the conditions between PV+ and PV-. But maybe what is happening is that moisture is condensing somewhere and causing a path to earth when the air cools at night. That will cause some current to flow such that the bus voltage goes up. Perhaps the circuit that detects that panels are present gets triggered by this. Indeed, enough current to earth from PV+ or PV- can trigger faut code 08 (bus voltage too high).

So maybe your problem is an electrically leaky panel. With great care, you might be able to confirm or deny that idea by hosing the panels after dark, perhaps watching activity on your phone, if that's possible.

On 2023/02/18 at 1:50 AM, Tonypee said:

  Should there be 31.5v at the pv input?  This is there even if the battery is disconnected. 

 

 

Yes, is normaly!, All inverters have that voltage there, at the PV input, it is normal, it is not a problem if it does not exceed the minimum accepted by the MPPT, in our case 90V. I saw that voltage in all inverters, with small differences, between 25V-45V.

 

Also, i have now in service 3 inverter 11kw all with fault F11, problem is from CONTROL BOARD.  They were installed in three-phase. will try to change memory on CB (Control Board)

Edited August 8, 20232 yr by mihaigsm2003

18 hours ago, mihaigsm2003 said:

 will try to change memory on CB (Control Board)

Hi again, today I changed the memories between 2 control boards and it seems that the cause of F11 is the memory chips . Problem solved!

Just be aware that all sorts of inverter-specific details are stored in those EEPROMs: serial number, many calibration constants, all settings.

7 hours ago, Coulomb said:

Just be aware that all sorts of inverter-specific details are stored in those EEPROMs: serial number, many calibration constants, all settings.

Serial number can be changed ! Settings also. also i read chips 24256, i put backup here. Use only memory 24256, or M24C256  32k

 

8Kw_good.bin 11kw_good.bin

6 hours ago, mihaigsm2003 said:

Serial number can be changed !

True, but not many people know the appropriate command (or how to change the data in the EEPROM directly).

The thing that concerns me is that the serial number is used as part of the authentication of the firmware, and there is a possibility of running into fault code 90 with unpatched firmware, and some patched firmware. A few models can't even be patched as the firmware update files are not yet available. You might be able to get your supplier to send you an appropriate setserial program that will fix it, but that takes time, and they will be wanting to make sure that you aren't running Voltronic firmware on a clone. Meanwhile, fault code 90 bricks the inverter.

I would check the result of the QBOOT command (you might need to use ATE0 to get it through, use AET1 afterwards to restore normal command flow). If it returns 0, then you are likely to get fault code 90 60 days after changing the serial number. The setserial programs send a mysterious and undocumented command with cryptographically generated parameters; it's not feasible for anyone other than Voltronic to use this command to normalise the EEPROM contents.

This is a hazard of living in the clone era, unfortunately.