Hi,

the MKS4 MPPT is sticky at 120v.

Is it possible to also patch this firmware?

Firmware version

74.02

 

Hi,

I do not understand your 2nd graphic.

The MPPT input voltage depends first on your PV array. Please inform.

I have 2 MKS 5K in parallel, the firmware is 74.04. So the behavior should be similar. My PV array (3 72 cell panels in series) deliver 100V to 110V when charging, OCV is around 130V. The charging voltage depends on the panels temperature, when heated up by the sun, the voltage lowers.

Beat,

Due to how Voltronic made the Firmware, the MPPT stay close to startup voltage (120v on this model) in the morning when it already could switch to higher voltage and could bring much more watts as its doing.

in the case of graphic2, when the MPPT is at 120v it brings about 60-100 watts only (out of a 4680w installed panels) and suddenly when the MPPT gets enough amps or any external kick (like grid power off/on or switch off/on PV Breaker) MPPT goes up to correct ~260v and work normally, watts jump to the power the panels can give according to weather situation. in the afternoon or after a cloud passes by it falls down and again hang around at 120v and some watts often for the rest of the day.

here its 3s8p 195w mono 72cells = 24 Panels = 4680wp

This is a known issue from other models and i hope this could maybe also patched for the MKS4.

5 hours ago, Beat said:

The MPPT input voltage depends first on your PV array.

It depends on the panel characteristics, yes, but also on how hard the MPPT loads the panel. It can go way past the maximum power point (attempting too much current, resulting in too low voltage, and hence too low power).

I have firmware version 74.03, and it should be a one byte patch to fix this (plus two more for the version number change, and one more to fix the premature float bug). I don't have time to do it tonight (actually morning). Post again if I forget. Or maybe @Georg594 can do it, if he can find the firmware update file.

For whatever reason, the minimum MPPT voltage defaults to 120 V for this model, so the "stuck at 90V" bug seen in other models becomes a "stuck at 120 V" for this model.

I wonder if Voltronic will ever admit that there is a problem. Spending all day at 120 V is going to roughly halve your solar energy for the day (on cloudy days; maybe they only test in sunny conditions).

2 hours ago, Coulomb said:

I wonder if Voltronic will ever admit that there is a problem.

i reported the MPPT sticky issue for MKS4 and Max1 8k to the Voltronic Dealer. Zero response concerning this since a weeks.

Its time for the GCAAOS
George & Coulomb Advanced Axpert Operating System

🙂

Thank you so much, without you these Inverters would be a case for the trashbin.

 

On 2022/12/04 at 1:14 AM, Coulomb said:

I have firmware version 74.03, and it should be a one byte patch to fix this (plus two more for the version number change, and one more to fix the premature float bug).

Here is patched firmware version 174.03, based on factory firmware version 74.03. Will only work with '2809 processors. For Axpert MKS IV 5.6kW only, NOT FOR Axpert VM IV, which looks a lot like it. The VM IV uses a smaller processor, which doesn't have enough flash space for this firmware.

This patch implements only one of Georg's suite of patches to avoid the "stuck at 90V" bug (which is here a "stuck at 120V bug). It also fixes the premature float bug. It will show as U1 74 03 on the display, but should show as version 174.03 on monitoring software.

[ Edit: Note that the file dsp_173.03.hex is actually version 174.03, so it should have been named dsp_174.03.hex. Sigh. But with the old reflash tool, you don't have to choose the file name anyway. ]

Use at your own risk.

dsp 174.03 3 patched 2809.zip

Edited December 31, 20223 yr by Coulomb

On 2022/12/03 at 12:57 PM, mjmx8k said:

here its 3s8p 195w mono 72cells = 24 Panels = 4680wp

I still do not understand. My PV array (3 72 cell panels in series) deliver 100V to 110V when charging, OCV is around 130V. I do not understand how it can get anywhere near 200V. Am I missing something?

20 minutes ago, Beat said:

I still do not understand. My PV array (3 72 cell panels in series) deliver 100V to 110V when charging, OCV is around 130V. I do not understand how it can get anywhere near 200V. Am I missing something?

The same what I saw. My 3S also at 102V no load and down to about 87V at nearly full power on the Axpert. When I run them 6S for my grid tied they never exceed 205V and around 165V in summer under full load.

 

45 minutes ago, Beat said:

Am I missing something?

What you're probably missing is that these guys have the higher voltage SCC models, so they have at least 4 panels in series, often 6 and up to about 10. These models boost the PV voltage up to the bus voltage, whereas the SCCs we have buck the panel voltage down to battery voltage.

I'm not sure, but I suspect that their SCCs use panel power to power the electronics (gate drivers, measurement op-amps etc), whereas ours use battery power once panel voltage is detected. I suspect that this may be part of the problem: when the panel power is low, they may have to do some tricks to make sure that the power supply gets "kick started".

On 2022/12/03 at 12:57 PM, mjmx8k said:

Beat,

 

here its 3s8p 195w mono 72cells = 24 Panels = 4680wp

This is a known issue from other models and i hope this could maybe also patched for the MKS4.

@Coulomb

Yes I did see it but it was written that 3S8P is used.

No assumption about the connection.

Edited December 4, 20223 yr by Scorp007

as untechnically as possible:

3 Panels around 36v each give you around 110v and it would not go much higher in any way on load.
but 8 Panels around 36v gives about 280v

The Axpert MKS4 has startupl Voltage of 120v and goes up to 450v (e.g. you could use 12x 36v Panels)
so 3 panels could be even hard to start the MKS4

The MKS4 (and others) have the problem that it stays too long (for these 3x8Panels) at 120 volt and therefore loose out real watts.

Grid connected inverters work differently and they try to find a Power Point close to the grid voltage to do as less conversion as possible, so they try to go close to 230 Volt (Europe Grid Voltage)

3 hours ago, Scorp007 said:

Yes I did see it but it was written that 3S8P is used.

I think there is an error in translation here... I think he means "3 strings of 8 panels", not "3 series, 8 parallel" like we are used to here on the forum.

40 minutes ago, jumper said:

I think there is an error in translation here... I think he means "3 strings of 8 panels", not "3 series, 8 parallel" like we are used to here on the forum.

Well spotted. The 3 series gives just below 120V and then 8 series close to 260V as was shown on the graphs in the 1st posting. 🤔

10 hours ago, Scorp007 said:

Well spotted. The 3 series gives just below 120V and then 8 series close to 260V as was shown on the graphs in the 1st posting. 🤔

Yeah that's the problem they have discovered here, that the mppt gets stuck at 120V in bad weather even if there is over 250V available resulting in a major loss of output. The first graph is a zoom of the beginning of the second graph showing the 120V flatline which happens again in the afternoon.

There have been a lot of interesting developments on this thread worth reading: 

 

Edit: More here too: 

 

Edited December 5, 20223 yr by jumper

21 hours ago, jumper said:

I think there is an error in translation here

sorry to confuse, i always type this wrong. should have been 3P8S
 

50 minutes ago, mjmx8k said:

sorry to confuse, i always type this wrong. should have been 3P8S
 

All good, I think 8S3P would be even less confusing 😀

@Coulomb

please could you make me for the MKS4 a 74 03 where the float bug is fixed and where the MPPT amps is set to 0,20, no changes in the MPPT startup voltage.

 

Edited December 30, 20223 yr by mjmx8k

10 hours ago, mjmx8k said:

please could you make me for the MKS4 a 74 03 where the float bug is fixed and where the MPPT amps is set to 0,20, no changes in the MPPT startup voltage.

14 minutes to patch (it's quicker when I've done a similar patch before) and about the same to post it. Not too shabby 😎

This is patched main firmware version 274.03, based on factory firmware version 74.03, for the Axpert MKS IV with the '2809 processor (two voltage regulators on the control board). See Apxert Chipset Chatter to find out if your inverter is using the '2809 DSP chip. This firmware is NOT suitable for the Axpert VM IV, or the Infini V IV, both of which look very similar in outward appearance.

This patched firmware changes just three things:

1) The version reports as 274.03 on monitoring software, though still 74.03 on the front display

2) The premature float bug is fixed

3) The current threshold to transition from minimum MPPT voltage (here 120 V) to the actual maximum power point has been changed from 0.5 A (factory firmware), and 0.05 A (previous patched firmware, version 174.03), to 0.2 A in this version.

Use at your own risk.

 

dsp 274.03 3 patched 2809.zip

3 hours ago, Coulomb said:

14 hours ago, mjmx8k said:

please could you make me for the MKS4 a 74 03 where the float bug is fixed and where the MPPT amps is set to 0,20, no changes in the MPPT startup voltage.

14 minutes to patch (it's quicker when I've done a similar patch before) and about the same to post it. Not too shabby 😎

Its just amazing what you doing with adding value to raw binaries. 👌

@Coulomb

the Version 274.03 for the MKS4 works very well and stable.
its a huge improvement on cloudy days as it goes to higer voltage much earlier.

thank you for this!
 

@Coulomb

Upgraded with Version 274.03 and working well too.

Thank you !

Edited January 31, 20233 yr by boljul

Hello All

I have been scouring the forum for a while and just came across this topic using a different search. 

I have an axpert mks 4 that is only three weeks old and after 2 hours running it went off with an f12 dc dc overcurrent fault. I do not want to send it back to the supplier until I am certain it was something wrong with the inverter and not the install.

I have 7x 420w half cut panels in series, giving 256v dc and the limit on the inverter is 500v for the pv input. I have a pair of pylontech us5000 batteries giving 200 aH total. The whole kit is installed in a pre built cabinet with all of the protection devices and isolators installed on racking and in square boxing. The unit has an AC input and output on the side of the cabinet for supply to the property and the input from a generator or the mains as a standby.

When the system is running on solar only I get 255 v dc at the inverter connection with the inverter off and with it on I get between 350 and 450v dc. this is getting close to the limit for the pv input and I wondered if I should be worried at this high voltage. I am not really sure how these inverters work and I would be grateful if someone could tell me if this is an issue. I do not want the inverter damaging any of the other components. The bigger issue seems to be that when the p.v. is turned on, initially the inverter puts in 10 amps charge and in the sunshine initially about 900 watts of pv power. This only lasts a short while and the inverter goes into an F12 fault and the charge drops to zero.

After it re sets the system sits at near idle most of the day with the exception of a couple of peaks in the day where the rate has picked up a little but only 300 or so watts and 0.5 to 2 amps and only for a short while.

I can see there are a few of you that have a lot of experience with this inverter and I would welcome any advice before I take it out of the system and send it back to have it checked.

Thanks in advance

17 hours ago, bony999 said:

When the system is running on solar only I get 255 v dc at the inverter connection with the inverter off and with it on I get between 350 and 450v dc.

It sounds like the Solar Charge Controller is shorted, connecting bus voltage to the PV input. That will not be great for your panels, I would think, which would be operating as high powered infrared light emitting diodes.

It certainly sounds like a hardware inverter fault to me. However, I don't own one of these, so this is all theoretical.

7 hours ago, Coulomb said:

I would think, which would be operating as high powered infrared light emitting diodes.

Goodness, sending solar energy back to the sun, this got to be disturbing to our universe. 😎

Exporting Energy, thats what it does! 

Edited February 14, 20233 yr by BritishRacingGreen

Hello Both, thanks for the reply. I am somewhat concerned if the inverter is putting out power to the input of the array. Will this damage the panels as if the inverter is indeed faulty I don't want to be replacing panels too?

I have the inverter off at present pending returning it to the supplier for inspection, but given the lack of service from them so far I am expecting a bill to get it back and some excuse as to why it is broken. Given that there are only two cables in from the pv and two for the battery along side 2 purpose made in and out sockets it is hard to see where anything has been done that could do any damage. But I am sure they will find a way to make it my fault.

I am grateful for the replies and am hoping someone with knowledge of this inverter may be able to point me in the right direction.

Regards  Bony999