3 hours ago, stakoz said:

Hi CJB, welcome to the forum. Sorry to jump in but this topic is specific to an Inverter model being limited at 100amps when charging batteries. I note your queries are a bit different and there are other topics on stuck at 90v etc in this forum. Some of us are subscribed to specific topics, like myself on this one (as I have this specific issues of being limited at 100amps batteries charging) and again from the recent posts it is going offtopic and I receive email notifications for each post. But when I open the topic thread it diverts to other subjects. Would appreciate if you could please stay on the specific topic or look for specific topic threads related to your specific issues. Thank you in advance.

@stakoz hi you're welcome. I don't think it's off topic, this happened to me after the firmware update to solve the 90V block problems and I was wondering if it's normal or not. I'm referring to what I wrote previously. Did you read?

Hi @Coulomb , I would like to thank you again for the modified firmware dsp_373.63_patched_05_200V.
With the problem of 90-100V. Everything is working great now.
I could ask you for a modification for my inverter because of the battery charging only 100A.
I solved the temperatures by modifying the cooling and the MPPT voltage I have a max of 450V.
As you did in the previous post. Is it possible to modify this firmware with this improvement?
Thank you very much. I really appreciate your work

Ps: Axpert Max E 48V 11000W par-B (non twin)
U1 373.63
U2 12.28

Edited June 24, 20251 yr by lada.cb

It seems that at low MPPT voltage the power goes above 100 A

Yes, same with me, early mornings I get for about half hour sometimes up to 130-140 amps charging current for the batteries, then it caps at 100 amps . Possibly due to the restrictions discussed before, my inverter often goes to 85 degrees centigrade then cools to 75 and again, and both my strings go to high PV voltage >400 volts (2p x 9s x450v PV panels on each of the two strings situated East/West. I am tempted to request firmware re-write but concerned about possible safety issues as the inverter works at its max late morning and early afternoon at 11000 W. My batteries are around 43kwh.

17 hours ago, stakoz said:

Yes, same with me, early mornings I get for about half hour sometimes up to 130-140 amps charging current for the batteries, then it caps at 100 amps . Possibly due to the restrictions discussed before, my inverter often goes to 85 degrees centigrade then cools to 75 and again, and both my strings go to high PV voltage >400 volts (2p x 9s x450v PV panels on each of the two strings situated East/West. I am tempted to request firmware re-write but concerned about possible safety issues as the inverter works at its max late morning and early afternoon at 11000 W. My batteries are around 43kwh.

What's yours inverters? 80 it's crazy. Adjust cooling.
My Axpert Max E 11 kw
1. 3x Fan ARCTIC P14 Max + dust filter
2. regulation from aliexpress 
Temperature reduce from 57(64 very hot room) on 43 (47).

Hi everyone, over the weekend I tested the inverter with firmware modification from @KUBA.CZ (removing the 90/100A limit at higher MPPT

Everything was ok.

 The sun supplied more than 100A to the battery.

 The main purpose is to meet the peak demand from the battery. Because the inverter was cutting the max supply to 90A (100A), which is about 5500w. And when I had a demand of 6 kW, it switched to the grid. Now it's ok..

 

Thanks again L.

On 19.04.2025 at 12:56, kuba.cz said:

Deci, datorită lui Coulomb, am obținut exact firmware-ul 78.08 și am modificat pragul de reducere a puterii de la 360V la 450V, fișierul cu patch-ul este atașat.

Robert1968, poți să-l testezi, dacă dorești. Mult succes!

Notă pentru ceilalți care nu au citit subiectul: Nu știm de ce există acest tip de reducere a puterii și dacă este necesar. Utilizarea acestui firmware poate duce la o defecțiune catastrofală a invertorului. Utilizați-l pe propriul risc!

<font style="vertical-align: inherit;"><font style="vertical-align: inherit;">MAXE11K_TWIN_DSP_78.08_derate_at_450V.zip</font></font>

This patch have the modification of the 90v stuck ? @coulomb can modify this patch with derate to not block at 90v, for 200v minimum voltage on twice mppts ???

Hi @Coulomb, for max 11kw twin, u done to me 278.07 for the 90v problem, to 200v mppt. Can modify that firmware without derating pls ?

On 2025/06/26 at 6:46 AM, lada.cb said:

What's yours inverters? 80 it's crazy. Adjust cooling.
My Axpert Max E 11 kw
1. 3x Fan ARCTIC P14 Max + dust filter
2. regulation from aliexpress 
Temperature reduce from 57(64 very hot room) on 43 (47).

Hi Lada.cb, sorry for not replying earlier as I have been travelling, my inverter is tommatech 11kw, I have a lot of panels split into two separatestrings East and west 18x450w +18x450w, so this time in summer in Europe the inverter between 10am and 3pm can reach and stay all the time at 11kw max which may be the reason for the heating, also the current reaches also the max 17amps per string and gets capped. I have added external fans outside the inverter on top of the existing inbuilt ones, I believe they help but still inverter reached 85 degrees C then reduces power till it goes down to 75 C and again and again

4 hours ago, add1c7ed55 said:

This patch have the modification of the 90v stuck ? @coulomb can modify this patch with derate to not block at 90v, for 200v minimum voltage on twice mppts ???

Not this one, but I've modifed 278.07 for another member too. I'll send it to you in a message. So far, I have no reports of anyone testing it. Consider it to be highly experimental.

30 minutes ago, kuba.cz said:

Not this one, but I've modifed 278.07 for another member too. I'll send it to you in a message. So far, I have no reports of anyone testing it. Consider it to be highly experimental.

Hi Kuba.cz, could you please post the patched firmware here in the forum, once done, I may also decide to trial it, when my inverter is not on maximum sun harvest. Thank you

Okay, so due to high demand 😀 I'm posting it here. Hopefully it doesn't cause more harm than good. As always, make sure your battery (BMS) doesn't disconnect while charging - that seems to be the main risk here. Also I'd recommend to use at least two or three battery packs in parallel. Charging current over 100A would be a lot for a single 280Ah battery.

dsp_278.07_patched_200V_derate_460V.zip

1 hour ago, kuba.cz said:

Okay, so due to high demand 😀 I'm posting it here. Hopefully it doesn't cause more harm than good. As always, make sure your battery (BMS) doesn't disconnect while charging - that seems to be the main risk here. Also I'd recommend to use at least two or three battery packs in parallel. Charging current over 100A would be a lot for a single 280Ah battery.

dsp_278.07_patched_200V_derate_460V.zip

Hi Kuba.cz, thank you for this, I just checked and I am using the 273.63 firmware as modified by Coulomb on this forum, and it works great for my setup and number of panels including avoiding the stuck at 90v glitch. Would it be possible to to have this patched to avoid the battery limitation charge for 100amps, I have three battery banks in parallel each about 14kwh each. I am not sure the firmware you patched above (278.07) would fit my system, again the 273.63 works well except for the battery charge limit. Thank you in advance. Would be good if you also set up a "buy me a coffee" or a patron link so we can express gratitude and donate for your work.

1 hour ago, stakoz said:

I am not sure the firmware you patched above (278.07) would fit my system, again the 273.63 works well except for the battery charge limit.

I don't think these are interchangable. However I happen to have 373.63 modified already. Lada.cb asked me for this one about 10 days ago and reported it working correctly in this topic. Firmware file in the attachment.

1 hour ago, stakoz said:

Would be good if you also set up a "buy me a coffee" or a patron link so we can express gratitude and donate for your work.

Thanks in advance, I'll have a look at that.

dsp_373.63_patched_05_200V_derate_460V.zip

9 hours ago, kuba.cz said:

I don't think these are interchangable. However I happen to have 373.63 modified already. Lada.cb asked me for this one about 10 days ago and reported it working correctly in this topic. Firmware file in the attachment.

Thanks in advance, I'll have a look at that.

dsp_373.63_patched_05_200V_derate_460V.zip

Yes, charging works without problems. Test 130A. 
The inverter temperature is a maximum of 46 degrees after adjusting the cooling.
(adding fans 3x 140 mm, rotation slowly). 
I already have two batteries. So the charging will be divided.
Thanks again

Edited July 8, 2025Jul 8 by lada.cb

15 hours ago, kuba.cz said:

Ok, deci, din cauza cererii mari 😀, postez aici. Sper că nu face mai mult rău decât bine. Ca întotdeauna, asigură-te că bateria (BMS) nu se deconectează în timpul încărcării - acesta pare a fi principalul risc aici. De asemenea, aș recomanda utilizarea a cel puțin două sau trei pachete de baterii în paralel. Un curent de încărcare de peste 100A ar fi mult pentru o singură baterie de 280Ah.

<font style="vertical-align: inherit;"><font style="vertical-align: inherit;">dsp_278.07_patched_200V_derate_460V.zip</font></font>

Thanks a lot i have 3 pack of lfp 280ah..its enough. But im working on 18S not 16S, and now i charge to 62v, all is ok now. Do.u think if i will charge at same voltage 62v but with 150A will be too much for inverter ? Too much power and i can deffect it or it doesnt matter ?

42 minutes ago, add1c7ed55 said:

Thanks a lot i have 3 pack of lfp 280ah..its enough. But im working on 18S not 16S, and now i charge to 62v, all is ok now. Do.u think if i will charge at same voltage 62v but with 150A will be too much for inverter ? Too much power and i can deffect it or it doesnt matter ?

If the transformer ratio of this inverter is 1:8, then charging the battery at 62V would ask for 62*8+20=516V on the bus, which is way too high all by itself. It will probably trigger the overvoltage protection, which is usually at 490V, turning off the boost circuit temporarily. I'm not sure about the exact thresholds in this particular firmware, hopefully I'll find time to look at that later. However, it seems that your inverter is already working on the edge of its capabilities even without the derating disabled.

1 hour ago, kuba.cz said:

If the transformer ratio of this inverter is 1:8, then charging the battery at 62V would ask for 62*8+20=516V on the bus, which is way too high all by itself. It will probably trigger the overvoltage protection, which is usually at 490V, turning off the boost circuit temporarily. I'm not sure about the exact thresholds in this particular firmware, hopefully I'll find time to look at that later. However, it seems that your inverter is already working on the edge of its capabilities even without the derating disabled.

I can try to set the cherging power to 100A-110A-120A to test? And watch and verify the bus voltage to be under what voltage? This is the single problem? The bus voltage not to go to the upper limit ? Now i.have 475v the bigger ever.

I checked 78.07 and 73.63 and both seem to use 1:7.3 transformer ratio (surprisingly for me - I thought they always used integer ratios).

This means there should be around 473V on the bus while charging which is still ok and corresponds to what you are seeing.

The overvoltage threshold which temporarily disables the boost circuit is set to 490V and responds within one PWM cycle (like 50 microseconds), which is good. Some other versions keep waiting for multiple cycles before turning the boost circuit off.

Then there's another protection which throws the "Bus overvoltage" error if 500V is exceeded for more than 1 seconds. That should never happen as long as everything is working correctly.

So it seems quite possible ("safe" is probably not the right word 😀) to try to increase the charging current gradually, even with 18S batteries.

1 hour ago, kuba.cz said:

I checked 78.07 and 73.63 and both seem to use 1:7.3 transformer ratio (surprisingly for me - I thought they always used integer ratios).

This means there should be around 473V on the bus while charging which is still ok and corresponds to what you are seeing.

The overvoltage threshold which temporarily disables the boost circuit is set to 490V and responds within one PWM cycle (like 50 microseconds), which is good. Some other versions keep waiting for multiple cycles before turning the boost circuit off.

Then there's another protection which throws the "Bus overvoltage" error if 500V is exceeded for more than 1 seconds. That should never happen as long as everything is working correctly.

So it seems quite possible ("safe" is probably not the right word 😀) to try to increase the charging current gradually, even with 18S batteries.

Thanks. I ll try and come with feedback. Thanks

On 2025/07/08 at 10:37 PM, kuba.cz said:

I checked 78.07 and 73.63 and both seem to use 1:7.3 transformer ratio (surprisingly for me - I thought they always used integer ratios).

This means there should be around 473V on the bus while charging which is still ok and corresponds to what you are seeing.

The overvoltage threshold which temporarily disables the boost circuit is set to 490V and responds within one PWM cycle (like 50 microseconds), which is good. Some other versions keep waiting for multiple cycles before turning the boost circuit off.

Then there's another protection which throws the "Bus overvoltage" error if 500V is exceeded for more than 1 seconds. That should never happen as long as everything is working correctly.

So it seems quite possible ("safe" is probably not the right word 😀) to try to increase the charging current gradually, even with 18S batteries.

I made some tests, and at 130A cherging, all is ok, general temp is under 40C, and the bus voltage is 455V, only the chopper on mppt board is a little bit hot 45C.

The ambiental temp is 18°C.

And if i limit the charging i saw that the bus voltage is 475V cause the voltage of pv is bigger.

@Coulomb @kuba.cz

Hi. I have a problem with a 11kw inverter twin, comes with 78.08 oem firmware, i dont have the modifieded firmware 78.08 without the 90v stuck and derate 460v. I flash the 278.07 on it, and i have a problem with the voltage of battery, it drops when goes under 55v, it have 51v, even real is 54.5v and the inverter lost the serial, has 535555353.

I reflashed the oem.78.08 and all is ok.

Now i please u, can help me with modify the 78.08 with unblock the 90v and serate 460v ? Exactly like 278.07 that made for me?

6 minutes ago, add1c7ed55 said:

Hi. I have a problem with a 11kw inverter twin, comes with 78.08 oem firmware, i dont have the modifieded firmware 78.08 without the 90v stuck and derate 460v. I flash the 278.07 on it, and i have a problem with the voltage of battery, it drops when goes under 55v, it have 51v, even real is 54.5v and the inverter lost the serial, has 535555353.

I reflashed the oem.78.08 and all is ok.

Now i please u, can help me with modify the 78.08 with unblock the 90v and serate 460v ? Exactly like 278.07 that made for me?

I put here the 78.08 oem.

Thanks !!!

MAXE11K_TWIN_DSP_78.08.7z

On 2025/04/19 at 12:56 PM, kuba.cz said:

So thanks to Coulomb, I got the exact 78.08 firmware and changed the derating threshold from 360V to 450V, patched file attached.

Robert1968, you can test it, if you wish. Good luck!

Note for others who haven't read the topic: We don't know why this kind of derating is there and whether it is necessary. Using this firmware may lead to a catastrophic failure of the inverter. Use at your own risk!

MAXE11K_TWIN_DSP_78.08_derate_at_450V.zip

On 2025/04/19 at 12:56 PM, kuba.cz said:

So thanks to Coulomb, I got the exact 78.08 firmware and changed the derating threshold from 360V to 450V, patched file attached.

Robert1968, you can test it, if you wish. Good luck!

Note for others who haven't read the topic: We don't know why this kind of derating is there and whether it is necessary. Using this firmware may lead to a catastrophic failure of the inverter. Use at your own risk!

MAXE11K_TWIN_DSP_78.08_derate_at_450V.zip

Hi. Can someone modify the firnware 78.08 derate 460v with the blocking 90v disable ?

Thanks.

@Coulomb

MAXE11K_TWIN_DSP_78.08_derate_at_450V.zip

Can modify this with the 90v disable ? To be 278.08 200v without derate ?

Thanks

On 2025/04/19 at 12:56 PM, kuba.cz said:

So thanks to Coulomb, I got the exact 78.08 firmware and changed the derating threshold from 360V to 450V, patched file attached.

Robert1968, you can test it, if you wish. Good luck!

Note for others who haven't read the topic: We don't know why this kind of derating is there and whether it is necessary. Using this firmware may lead to a catastrophic failure of the inverter. Use at your own risk!

MAXE11K_TWIN_DSP_78.08_derate_at_450V.zip

@Coulomb hi again. Can modify this 78.08 derate 450v to be parched with 90v block with 200v too? Like 278.07.

Thanks a lot.

I have a problem with the new pcs of 11kw twin, dont works only with 78.08.