That probably means that the USB OTG upgrade method is not supported in this combination of display/DSP firmware. You would have to choose from the other two ones. RS232 should work in every case. And since there's a USB option in the reflash software, a USB cable should work too.

But, looking at the inverter status, your PV voltage is below 350V which means that the derating condition does not seem to be the reason for the charging current to be limited to 100A right now. In such case the patch won't help you. I know you already mentioned that you have parameter 02 (charging current) set to 150A. Then it does not make much sense to me. I'll have to look exactly where the battery_charging_current status value is being taken from.

Hi, Kuba.cz

Thanks for the support. :)

You assumed upgrade was not successful and you are probably right.
Can you please confirm based on screenshots, and U03 - this means upgrade error ?

So this is the screenshots from upgrade video.

Step 1: Upgrade approved: timestamp 0:15

Step 2 - timestamp 0:15 - 0:48 - button1 green led blinking (1 sec on 1 sec off.)

Step 3 - timestamp 0:48 - (Error??) message: U3

>But, looking at the inverter status, your PV voltage is below 350V which means that the derating condition
That strange why it says pv_input_voltage 328.6 V because PV2 is about 420V-440V.
All the Deshmonitor and WatchPower application report only one PV but MAX TWIN - his has TWO strings!

Probably this query shows only PV1 voltage which is usually under 350V.

FYI. - See the settings query:

root@beelink1:~# mppsolar --getsettings
Command: QFLAG - Flag Status inquiry
--------------------------------------------------------------------------------
Parameter                      Value          Unit
ac_input_voltage               230.0          V
ac_input_current               47.8           A
ac_output_voltage              230.0          V
ac_output_frequency            50.0           Hz
ac_output_current              47.8           A
ac_output_apparent_power       11000          VA
ac_output_active_power         11000          W
battery_voltage                48.0           V
battery_recharge_voltage       48.0           V
battery_under_voltage          47.0           V
battery_bulk_charge_voltage    55.3           V
battery_float_charge_voltage   54.0           V
battery_type                   User           
max_ac_charging_current        10             A
max_charging_current           150            A
input_voltage_range            Appliance      
output_source_priority         SBU first      
charger_source_priority        Only solar charging permitted
max_parallel_units             6              units
machine_type                   Off Grid       
topology                       transformerless
output_mode                    single machine output
battery_redischarge_voltage    54.0           V
pv_ok_condition                As long as one unit of inverters has connect PV, parallel system will consider PV OK
pv_power_balance               PV input max power will be the sum of the max charged power and loads power
max_charging_time_for_cv_stage 480            min
operation_logic                Automatic mode 
unknown_value_in_response_27   b'000'         
overload_bypass                enabled        
overload_restart               enabled        
lcd_backlight                  enabled        
primary_source_interrupt_alarm enabled        
record_fault_code              enabled        
buzzer                         disabled       
unknown_d                      disabled       
power_saving                   disabled       
lcd_reset_to_default           disabled       
unknown_l                      disabled       
unknown_n                      disabled       
over_temperature_restart       disabled       
--------------------------------------------------------------------------------

So i'll read the second and 3rd Upgrade option - unfortunately i have difficulties with windows.

Best Regards,
Robert

1 hour ago, robert1968 said:

Can you please confirm based on screenshots, and U03 - this means upgrade error ?

I'm not sure what that means. But quickly looking into the 38.17 display firmware I could only find "BDR96" and ":28062" (possibly also some other) reflash commands there, not "C28066" which your DSP firmware uses. So unless I missed something, then the USB OTG method can't work in this case.

2 hours ago, robert1968 said:

That strange why it says pv_input_voltage 328.6 V because PV2 is about 420V-440V.
All the Deshmonitor and WatchPower application report only one PV but MAX TWIN - his has TWO strings!

Oh, of course you're right. I forgot about the other string which is not shown there. The derating applies as soon as any of the strings exceeds 360V.

Is there a way to ensure which DSP i have?

Is there a linux based serial firmware update ?

I try ArenaINVReflashTool.exe tomorrow....

1 hour ago, robert1968 said:

Is there a way to ensure which DSP i have?

You would have to take the DSP board out and scrape the sticker off the chip. But there's no point, firmware version 78.08 can only run on TMS320F28066. And the reflash tool uses a specific command to enter the bootloader, which will also work only with this chip. You can see "FLASHCMD" defined in InvConfigFile.ini.

1 hour ago, robert1968 said:

Is there a linux based serial firmware update ?

I don't think so, this seems to be Voltronic's custom tool with no other alternative.

20 hours ago, robert1968 said:

So i assume maybe it does not run upgrade??

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.

Hi

Thanks for responding.

Unfortunately windows firmware update failed and inverter shows blinking 32 on the screen...

Inverter was powered off and on, but still blinking 32 on the screen.

Pls help 🥺

Edited April 21, 20251 yr by robert1968

Seems solved. Find another USB UART dongle (cp2102) and this seems working.

Upgrade running still.. :)

Edited April 21, 20251 yr by robert1968

Upgrade went smooth.

Seconds later I'm recoverd from heart attack:)

Now we are stable above 100A!!!

118A !

You did it Kuba.cz ! You are my genius 😍

Many many thanks 🙏!

Since here we should wait for see is this change is a success or failure - how the inverter tolerates the uprised load!

Fingers 🤞 crossing :)

121A :)

Edited April 21, 20251 yr by robert1968

I'm glad it finally worked out. Warning 32 means no communitaction between display and DSP, it was probably stuck in the bootloader because of communication error.

Looking forward to long-term test results 🤞

Yes. See longterm. But seems very promising, it went ~4 hours when battery full charged.

So the first test is proved the concept. Many thanks again for modifying fw ! :)

I'm curious which of the many temperature sensors has related to 100A derate.

Because I saw few temperature sensors are listed in serial queries. I will very wary for the next days.

13 hours ago, robert1968 said:

I'm curious which of the many temperature sensors has related to 100A derate.

I think it's the inverter_temperature and transformer_temperature which I called "inside" temperature in my previous post, because it's a sensor on the board, in some products not even close to any transformer.

inverter_heat_sink_temperatureonly takes the higher of the two values inverter_temperature and battery_temperature.

scc_pwm_temperature will limit PV current if it exceeds 80 deg.

On 2025/04/20 at 7:54 AM, Coulomb said:

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.

Hi. Can u modify your firmware 278.07 for max 11k twin to be without derating ?

U modified for me last year for the 90v stuck..and now if can charge with max ampers...will be super.

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.

On 2025/04/24 at 7:36 AM, Coulomb said:

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.

My inverter stays all the time under 50°C, cause i have an AC behind it, that works all the time, verified on Solar Assistant. I think all will be ok, only if we will test it will know all is safe.

U have other things in mind that u think can make problems if disable that derating???

6 hours ago, add1c7ed55 said:

U have other things in mind that u think can make problems if disable that derating???

Yes, DC bus voltage regulation. The PV voltage is boosted and becomes the bus voltage. It may be that if you allow a lot of PV power at high PV voltage, the firmware may not be able to keep the bus voltage inside safe limits.

Can you monitor the bus voltage on yours? It's available via the QPIGS command, which only works for the inverter that the monitoring software is connected to. Solar Assistant and others probably use the QPGS command, which can get information about all paralleled inverters, but does not have the bus voltage (per the documentation I looked up quickly; it could well be inaccurate).

10 minutes ago, Coulomb said:

Da, reglarea tensiunii magistralei DC. Tensiunea PV este mărită și devine tensiunea magistralei. Este posibil ca dacă permiteți multă putere fotovoltaică la tensiune fotovoltaică ridicată, firmware-ul ar putea să nu poată menține tensiunea magistralei în limitele de siguranță.

Poți monitoriza tensiunea magistralei pe a ta? Este disponibil prin comanda QPIGS, care funcționează numai pentru invertorul la care este conectat software-ul de monitorizare. Solar Assistant și alții folosesc probabil comanda QPGS, care poate obține informații despre toate invertoarele în paralel, dar nu are tensiunea magistralei (conform documentației pe care am căutat-o rapid; ar putea fi inexacte).

Yes, in full light of sun, i have 475v on dc bus voltage, cause i have 2 strings of 450v each. And i have battery on 60v pack, 18s. I think it have enough force and resources to keep the dc bus voltage up enough.

7 hours ago, add1c7ed55 said:

I think it have enough force and resources to keep the dc bus voltage up enough.

I expect the problem would be with overshoots on the DC bus, i.e. going over 500 V. Axpert control loops are notorious for overshoots.

5 hours ago, Coulomb said:

Mă aștept ca problema să fie cu depășirile pe magistrala DC, adică trecând peste 500 V. Buclele de control Axpert sunt renumite pentru depășiri.

Logicaly if i charge with more amps, the voltage of pv goes down right ? More amps less voltage, then the dc bus voltage goes down not up...is not working like this ?

52 minutes ago, add1c7ed55 said:

Logicaly if i charge with more amps, the voltage of pv goes down right ? More amps less voltage, then the dc bus voltage goes down not up...is not working like this ?

Normal convention it will be as explained. We do however deal with the MPPT which will strive to find the best spot for voltage and current to yield the highest PV power.

3 hours ago, Scorp007 said:

Convenția normală va fi așa cum sa explicat. Cu toate acestea, avem de-a face cu MPPT care se va strădui să găsească cel mai bun loc pentru tensiune și curent pentru a produce cea mai mare putere fotovoltaică.

Ok. Then its safe to disable the derating options or not?

15 hours ago, add1c7ed55 said:

Logically if I charge with more amps, the voltage of PV goes down right ? More amps less voltage, then the DC bus voltage goes down not up...is not working like this ?

That's true. But to me the dangerous situation is when there is high PV power, then suddenly there is a large decrease in load that the PV was supplying, either in whole or in large part. Now as the control system tries to "turn off the tap", that very VI curve means that as the power is reduced, the voltage is increasing. So if the bus voltage is getting dangerously high, then the only option to lower it is to dump some of the energy presently stored in the bus capacitors into the battery. [ Edit: Not quite; see next post. ] I have no idea how models with no battery cope with this. Maybe that's why they want a lowered battery charge limit when the PV voltage is high, so that they always have the option of exceeding their self-imposed limit without exceeding the limit set by the customer. If we allow full current at high PV voltage, then that option is no longer there; to make the bus voltage safe, the firmware would have to exceed the customer set limit, which might damage the battery.

The effect of exceeding the limit whenever a large load turned off would be pretty small, I think, and would have negligible effect on battery life.

11 hours ago, add1c7ed55 said:

Then its safe to disable the derating options or not?

That's the big question. Did they limit the current because they rushed the firmware, or because there is an important safety / reliability / other reason? Unfortunately, I don't know the answer.

If you watch your bus voltage in the inverter with the disabled derating after a drop in load and the battery current surge isn't excessive, then it seems to me that it's safe. But there may be other scenarios that I haven't thought of.

I still want to go through some other firmwares to see how common this derating limit is. I haven't gotten around to that yet.

Edited April 27, 20251 yr by Coulomb
Note to see next post. Sigh.

3 hours ago, Coulomb said:

So if the bus voltage is getting dangerously high, then the only option to lower it is to dump some of the energy presently stored in the bus capacitors into the battery.

Actually, this is not true. The full bridge can puff a little energy back into the AC-in source to trim the bus voltage, if of course an AC-in source is present.

So far: firmware version 90.06 (for an 8kW Max) limits the charge current to 80A if PV voltage is >360V and AC-in is not present, and does not limit otherwise (based on PV voltage; there are several other kinds of derating).

Firmware 78.08 (for 11kW Maxs, 24th Jun 2024): if the PV voltage exceeds 360V: charge current is limited to 100A if AC-in is present, and to 90A if AC-in is not present. It also limits the charge current to 100A if the AC-in voltage is greater than 250 VAC, presumably because puffing in energy to that would make the voltage really high. Now that I can follow this part of the firmware code, I can check some more firmwares to see what they do. 90.06 is from 2022; I use it because it's my best commented Max firmware disassemly.

Firmware 63.04 (for Max E 11kW non-Twin, 2023): Same as for 78.08.

Firmware 46.82 (for Max E 8kW non-Twin, 2023): Same as for 90.06 (both of these are 8kW firmwares).

Firmware 72.08 (for Max E 8kW non-Twin, 23rd Oct 2024, latest I have): Same as for 90.06.

Firmware 81.08 (for 8kW Max II non-Twin 23rd Oct 2024, latest I have): Same as for 78.08.

So it looks like the 8kW firmwares for the E models don't restrict the maximum charge current at all if the PV voltage is > 360 V and AC-in is present. Yet the one Max II model I looked at does! And two firmwares with hex files dated the same day have different algorithms.

I'll need to look into this a bit further.

Edit:

Firmware 82.63 (For Max II 10kW non-Twin, May 2024): Same as for 78.08.

Firmware 63.04 (For Max II 11kW non-Twin, 5th Sep 2023, earliest 11kW firmware I have): same as 78.08.

Firmware 45.14 (For Max E 7.2kW non-Twin, 5th Nov 2024, latest 7.2kW firmware I have): No derating based on PV voltage that I can find at all!

Firmware 50.17 (For King II 5kW 5th Nov 2024, latest King II firmware I have): The firmware is very different, and does not appear to limit the charge current based on PV voltage.

Firmware 52.10 (for MKS IV 5.6kW 10th July 2024, latest MKS IV firmware I have): Different, less so than the King II firmware, but also does not seem to derate the charge current based on PV voltage.

Edited April 28, 20251 yr by Coulomb

6 hours ago, Coulomb said:

Este adevărat. Dar, pentru mine, situația periculoasă este atunci când există o putere PV mare, apoi brusc are loc o scădere mare a sarcinii pe care o furniza PV, fie în totalitate, fie în mare parte. Acum, pe măsură ce sistemul de control încearcă să „închidă robinetul”, acea curbă VI înseamnă că, pe măsură ce puterea este redusă, tensiunea crește. Deci, dacă tensiunea magistralei devine periculos de ridicată, atunci singura opțiune de a o reduce este să aruncați o parte din energia stocată în prezent în condensatorii magistralei în baterie. [ Edit: Nu chiar; vezi postarea urmatoare. ] Nu am idee cum fac față modelelor fără baterie. Poate de aceea își doresc o limită scăzută de încărcare a bateriei atunci când tensiunea fotovoltaică este mare, astfel încât să aibă întotdeauna opțiunea de a-și depăși limita autoimpusă fără a depăși limita stabilită de client. Dacă permitem curent complet la tensiune fotovoltaică mare, atunci acea opțiune nu mai există; pentru a asigura siguranța tensiunii magistralei, firmware-ul ar trebui să depășească limita setată de client, ceea ce ar putea deteriora bateria.

Efectul depășirii limitei ori de câte ori o sarcină mare este oprită ar fi destul de mic, cred, și ar avea un efect neglijabil asupra duratei de viață a bateriei.

Asta e marea întrebare. Au limitat curentul pentru că s-au grăbit cu firmware-ul sau pentru că există un motiv important de siguranță/fiabilitate/altfel? Din păcate, nu știu răspunsul.

Dacă vă uitați la tensiunea magistralei în invertor cu deratingul dezactivat după o scădere a sarcinii și creșterea curentului bateriei nu este excesivă, atunci mi se pare că este sigur. Dar pot exista și alte scenarii la care nu m-am gândit.

Încă vreau să trec prin alte firmware-uri pentru a vedea cât de comună este această limită de derating. Încă nu am ajuns la asta.

Toate 11kw si 8kw voltronic au aceasta limitare. Le am testat pe toate. For me its not problem for battery, i have 60kwh LFP, almost 1000Ah, then can charge with maximum power.