Jump to content

Axpert MKS II 5kW Error 08


Recommended Posts

I have an Mecer Axpert MKS II 5kW inverter.  The one that can take up to 450V DC Solar input.

Every now and then Error 08 appears - bus voltage too high.  It always happens at night, so the solar panels are not the source of the problem.

The problem is that the thing basically shuts down and does not recover.  It is very irritating since it needs a manual reset.  Until it is reset, the house has no power!!!  What will happen if I am on vacation and this happens???

I have installed it in July 2019 and it has happened  6 times since then - one time 3 nights in a row.  I did not get much sleep - very grumpy :(

It is running firmware 71.71.  Could that be the problem?  Some service manual suggested that...

Or is the bus voltage sensor (resistor splitter I guess) too sensitive?

Watch Power does not tell me anything more than "Bus voltage too high".  Unfortunately I do not have a spare laptop that I can leave connected to the inverter to continuously monitor it....

I have had thoughs of ripping this thing out and installing something else - it is driving me nuts to have an unreliable system that costs a fortune...

Link to post
Share on other sites
  • Replies 205
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Popular Posts

@charlez - I don't think the suppliers are even aware of this issue with the inverter! Here is the circuit The heart of the isolater, is the LD03-16B12 (AC/DC Converter Vin = 90-528VAC

I did put up a fuss with Voltronic themselves regardings this issue.  At first they gave me a lame answer as follows : "Per your information below, it means error 08 was caused by the surge from

@charlez has pointed me to this information from the official Axpert MKS II manual: 14. WARNING: Because this inverter is non-isolated, only three types of PV modules are acceptable: single cryst

Posted Images

3 hours ago, APV said:

Every now and then Error 08 appears - bus voltage too high. 

It would be good to know if the bus voltage really is too high, or it's a measurement error. But these are fairly advanced things; don't mess with 400+ VDC unless you know what you are doing. You would need a multimeter measurement of the bus voltage, at about the same time as a QPIGS command has reported the measured bus voltage. It's field 9 of the QPIGS output, between Output load percent and battery voltage. If these are significantly different, then yes, it could well be the high value resistors that measure the bus voltage. There may be dust or something shunting these high value resistors, though the conformal coating on the board should prevent this sort of problem. The resistors could simply be faulty or the wrong value part was used. Ironically, these things cost less than US$0.01, yet the labour to find and replace them could cost 10 000 times as much.

3 hours ago, APV said:

It is running firmware 71.71.  Could that be the problem? 

I don't know this firmware well. I don't have a later version than that.

I'd see if you can get it replaced under warranty or repaired by Mecer.

3 hours ago, APV said:

I have had thoughs of ripping this thing out and installing something else - it is driving me nuts to have an unreliable system that costs a fortune...

Unfortunately, any replacement is likely to cost a lot more.

Link to post
Share on other sites
10 hours ago, Coulomb said:

It would be good to know if the bus voltage really is too high, or it's a measurement error. But these are fairly advanced things; don't mess with 400+ VDC unless you know what you are doing. You would need a multimeter measurement of the bus voltage, at about the same time as a QPIGS command has reported the measured bus voltage. It's field 9 of the QPIGS output, between Output load percent and battery voltage. If these are significantly different, then yes, it could well be the high value resistors that measure the bus voltage. There may be dust or something shunting these high value resistors, though the conformal coating on the board should prevent this sort of problem. The resistors could simply be faulty or the wrong value part was used. Ironically, these things cost less than US$0.01, yet the labour to find and replace them could cost 10 000 times as much.

  • Don't worry!  Us South Africans are not scared of 400V DC :)
  • OK, so I got a Python script working to send the QPIGS command, opened up the inverter and did my tests.  The voltage differs by 1-2V between my multimeter and what the script says.  Firstly, I hope I was measuring at the correct point - just took a wild guess!  See the attached picture where I did my measurements.
  • Since the problem only occurs at night when my house is not using much power - less than 30W, I decided to disconnect the house.  Under load, the bus voltage is about 440V and fairly constant.  When the load is disconnected, it starts jumping around a bit - from 430V to about 485V!!!

I don't know this firmware well. I don't have a later version than that.

I'd see if you can get it replaced under warranty or repaired by Mecer.

  • Not sure what the warranty period is.  This one was manufactured more than a year ago. But it is void in any case now that I have opened the case.  I shall undertake any repairs myself as far as possible...

Unfortunately, any replacement is likely to cost a lot more.

  • True.  I wonder why the other brands are so much more expensive?

 

bus2.jpg

Link to post
Share on other sites
12 hours ago, APV said:

Don't worry!  Us South Africans are not scared of 400V DC :)

I hope that's fierce independence born of necessity and not foolish nievity 😮

12 hours ago, APV said:

The voltage differs by 1-2V between my multimeter and what the script says.

Brilliant! So that rules out a measurement error.

Quote

Firstly, I hope I was measuring at the correct point - just took a wild guess!  See the attached picture where I did my measurements.

I've not seen inside an Axpert MKS II. That certainly looks correct, where the Solar Charge Controller connects to the DC bus. That also explains the two large holes in the mother board on Axpert MKS (non II) models: it's the same main board used for the two different models. Neat.

12 hours ago, APV said:

When the load is disconnected, it starts jumping around a bit - from 430V to about 485V!!!

Some variation is to be expected. I note that the bus voltage usually sits at around 8.0 times the battery voltage, because of a 1:8 transformer ratio. That would mean that your battery voltage is sometimes rising to some 485/8 = 60.6 V. Is it possible that you have a lithium battery with a BMS, and that the BMS is disconnecting due to overvoltage?

Link to post
Share on other sites
15 hours ago, Coulomb said:

I hope that's fierce independence born of necessity and not foolish nievity 😮

  • Yes - independant to the extreme :()

Brilliant! So that rules out a measurement error.

I've not seen inside an Axpert MKS II. That certainly looks correct, where the Solar Charge Controller connects to the DC bus. That also explains the two large holes in the mother board on Axpert MKS (non II) models: it's the same main board used for the two different models. Neat.

Some variation is to be expected. I note that the bus voltage usually sits at around 8.0 times the battery voltage, because of a 1:8 transformer ratio. That would mean that your battery voltage is sometimes rising to some 485/8 = 60.6 V. Is it possible that you have a lithium battery with a BMS, and that the BMS is disconnecting due to overvoltage?

  • No, I am using 4x 180AH lead acid batteris in series.  No BMS.  Normally when this problem occurs, the battery voltage is around 51V.  So according to your statement, the bus voltage should be around 408V at that time.  Most certainly not 500V!!!  Maybe my transformer has a couple of extra windings on the secondary, or a couple less on the primary :)??  Maybe it is time to modify the transformer.  I wish I had a circuit diagram for this beast....

 

Link to post
Share on other sites
5 hours ago, Quat Allah Alshams said:

Just out of curiosity

Please tell us whats the spec of your panels and how are they connected

Well, as I have said, the problem only occurs at night.  No solar input. causing the issue.

However, to answer your question.  I have 2 banks of 7x400W panels in series, connected in parallel.  Thus giving me maximum open circuit voltage of about 350V DC and a maximum current of 20A, at least theoretically.  Also a theoretical power of 5600W.  For these cloudy days, you know :) I am aware that it exceeds the maximum solar input of the Axpert (4500W), but the Axpert only uses up to 4500W.  I have tested it...

Edited by APV
Link to post
Share on other sites

Right, the problem just happened now.  At 23h45.  Fortunately I was still awake and using Windows.  Rebooted into Linux, connected the inverter to my laptop and started monitoring.

Oh man!   At this stage, I was using about 400W.  The bus voltage just goes up and up until it hits 500V, at which point the inverter reboots.  After the reboot, the bus voltage is about 390V.  Then the cycle repeats.  This happens 3 times, at which point Error 08 kicks in and the inverter shuts down.

This must be some firmware bug.  I cannot see how normal electronics would go out of control like this.  Here is my monitoring screen just before a shutdown (after I have switched my house to utility.  Temperature and grid voltage, as well as battery voltage are fine.

 

.626091060_Screenshotat2019-12-1923-52-06.png.a986a06d9dc3ae92a6c8696e0502c7eb.png

 

Link to post
Share on other sites
4 hours ago, APV said:

This must be some firmware bug.  I cannot see how normal electronics would go out of control like this.

It could be the bus soft start power supply not turning off. With a reasonable load, this power supply would not be able to push the bus voltage too high. At night with low loads, it might be able to sneak up the bus voltage before the firmware can do anything about it.

What the firmware usually does about high bus voltage is to switch to bypass mode (internally different from normal bypass mode, this mode is only for when the bus voltage is too high). It then does something special, I assume it pumps energy back into the battery, until the bus voltage is low enough again.

You could take a look at the partial schematic trace of the bus soft start circuit, and see if it seems to be active when it shouldn't. It should be inactive all the time, except for a few seconds after start-up. [ Edit: presuming the Axpert MKS II is similar to the Axpert MKS non-II, which I believe is the case. ]

Edited by Coulomb
Link to post
Share on other sites

There is a ghost in my machine!

It has not done it since my last post.  Just as a reference, I have now measured the bus voltage while the beast is in standby mode.

With, or without load, the bus voltage is rock solid at 366V.

So I ask you with tears in my eyes:  Why, o why, does it spiral out of control once in a blue moon?  Does anyone have a number for Ghost Busters??? :)

 

Link to post
Share on other sites
On 2019/12/26 at 7:19 AM, APV said:

With, or without load, the bus voltage is rock solid at 366V.

That actually sounds a bit low; 366 / 8 = 45.7 V. [ Edit: but this would be a 64 V model, so 366 / 7 = 52.3 V, a perfectly normal battery voltage. ] So maybe it's generally a problem of poor regulation of the bus voltage (as opposed to always too much bus voltage, if any).

Unfortunately, that isn't suggesting any solutions to me at this stage.

Edited by Coulomb
Link to post
Share on other sites

Where do I find the bus soft start circuit?  My ghost has hit again.  As far as I can see, there are 5 boards.

1.  Main board with the IGBT's and heat sinks.

2. SCC board on top of the heatsinks.

3. Control board plugged into the main board, located at the left side.

4. Unknown board at bottom left.  Contains 4 MOSFETs without heatsinks.  Connected via 4 stand offs to main board and has a connector cable.  See attached photo.

5. Interface board for PC link and parallel connectors.BordXa.thumb.jpg.2dce67849c8994937cdbdb36f290f317.jpg

Link to post
Share on other sites
19 hours ago, APV said:

Where do I find the bus soft start circuit?

1.  Main board with the IGBT's and heat sinks.

That's the one. See below.

19 hours ago, APV said:

4. Unknown board at bottom left. ... See attached photo.

That's a board to effect the fast changeover from grid to battery modes. It's sometimes confusingly called a "parallel" board. It's nothing to do with paralleling inverter-charger units (that's a sixth board).

19 hours ago, APV said:

5. Interface board for PC link and parallel connectors.

These are actually two boards, almost on top of each other. The PC link board is commonly called the comms or communications board; the other one is the parallel or paralleling board.

The bus soft start circuit involves major components TX2, Q6, and D65, as shown in the partial schematic trace. I'm only 95% sure of the location of D65. This photo is from a very old (2013) machine, which still had the AC power supply (hence TX6 and associated components still existed). So your main board will probably differ a little.

337003951_Bussoftstartcircuitlocation.thumb.jpg.a4975bfbd14944a00d39f9b92e7d96f4.jpg

Link to post
Share on other sites

I want to add that I have the same inverter. It was installed in May 2019, so still under warrantee.

It ran for 6 months no problem, then started with the exact same problem as described here.

I took it back to Mustek. They did a FW upgrade. Worked for a month then the problem re-appeared. Now shuts down every 2 weeks.

Voltronic have a design issue here

Regards,

eLEK

MKii.jpg

Link to post
Share on other sites

Hmm, I think I must consider modifying the bus start circuit.

If only the stupid problem would reappear!  After I have removed the "Unknown Board" to take the photo - see previous post - and reattached it, tightening the standoffs as much as I could, the problem has not reappeared.  2 of them were somewhat loose...

What is your current firmware version?

I presume you did not get a copy of the firmware???

Link to post
Share on other sites
13 minutes ago, APV said:

If only the stupid problem would reappear! 

Be careful what you wish for... 🤐  (smiley with zipper mouth)

Quote

After I have removed the "Unknown Board" to take the photo - see previous post - and reattached it, tightening the standoffs as much as I could, the problem has not reappeared.  2 of them were somewhat loose...

I'd love to believe that the fast changeover board was the problem, but as far as I can see it merely parallels some relays with some TRIACs or similar. No connection (electrical or other) that I can think of.

Quote

What is your current firmware version?

Yes, @[email protected], it would be nice to know what version you updated from and to.

Quote

I presume you did not get a copy of the firmware???

And Coulomb is always interested in firmware files. Always. 😎

I've just seen your reply. Alas, I already have 71.71. 😢  I'm pretty sure it is available for download somewhere.

Edited by Coulomb
Link to post
Share on other sites
  • 4 weeks later...

Hi @APV

I have the same inverter, Axpert MKS II 5kw (Kodak branded) with two Narada 100ah 48v 4.8Kw Lithium Ion Batteries, two 6 panel Canadian solar 330wp panels, and have the same problem. 

Seems to happen in early morning after its been on grid mode for a few hours, typically when the batteries have not been able to charge fully (but also randomly if this condition holds) the day before due to cloud.

Hope this info is of some help but would love to know of a solution!

Charles

Link to post
Share on other sites
7 hours ago, ROMAN KHAN said:

My vm 3kva plus inverter has a problem,it shows fault code 08 on utility charging, it is ok on solar and battery mode but shows fault08 on utility charging. Please explain where the fault would be

There have been several of these lately. The cause is not known. It might be a recent firmware bug. Is yours made in the last year or so?

Link to post
Share on other sites
On 2020/02/01 at 6:56 AM, BvR said:

I spoke to a Axpert supplier in Cape Town. They indicated that they replace the main board when they see this problem. Seems to solve it

Who did you speak to?  It would be good to know where one can obtain spares in this 3rd world country of ours...

Link to post
Share on other sites
  • 1 month later...

Just an update. So the mainboard on my MK-II was changed by the supplier and the unit was reinstalled.

To my utmost frustration the legendary  Error 08 appeared within 5 days.

It is futile for us to try and solve this.

Voltronic must come up with a remedy, but their standard response is to get a 'firmware update', however my inverter was already upgraded by the supplier.

We must now make a noise towards Voltronic with this

Regards

 

Edited by BvR
correct spelling mistakes
Link to post
Share on other sites

I have a new Full Circle Solar 5kW inverter.  I think it is a Voltronic VMII. Running firmware 20.13, which the supplier says is the latest. 1 Narada 48V, 100A LFP battery, and no solar (only used as a UPS).  Still under warranty, and running test after test for the supplier, trying to trace the issue...

Also getting these 08 errors.  They have occurred numerous time, but in 2 situations:

1) Charge current set to 20A. Battery fully charged, grid connected, on bypass around 400W load between midnight and 2AM.

2) Charge current set to 60A. Load 2000W. Run on battery for 15 minutes, then reconnect grid. Error 08 occurs after around 10 minutes when it goes from CC to CC charge (charge current starts ramping down).

It has not (yet) occurred with charge current set to 10A.

The battery never shows an alarm light (which I assume it would if the BMS had tripped).

Not sure if this is the same issue as the others are having.  The symptoms make no sense to me, unless BMS is cutting the battery and voltage is spiking...

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...