Axpert MKS II

[Louis0852]

I have a question regarding the Mecer/Voltronic Axpert MKS II inverter setup in parallel with Pylontech batteries?

 

So the setup is as follows:

2x Axpert MKS II Inverters coupled in Parallel

8x pylontech US2000B batteries

Centurion Solar ICC

 

Problem: Everything works perfectly during times when the battery capacity is not 100%. As soon as the batteries are fully charged at 100% and the PV runs the loads that remain during sunshine hours, the inverter gives me an error (03) which is battery voltage is too high. During this time the inverters switch off for a while and come back on after about 30 seconds. The settings suggested that were given to me by the supplier is the following:

Setting 1: SBU

Setting 2: 80A

Setting 3: APL

Setting 4: Disabled

Setting 5: USE

Setting 6: Disabled

Setting 7: Disabled

Setting 8: Default

Setting 9: Default

Setting 11: 80A

Setting 12: 46V

Setting 13: 50V

Setting 16: OSO (Solar Only)

Setting 18: Alarm Off

Setting 19: Default

Setting 20: Default

Setting 22: Off

Setting 23: Disabled

Setting 25: Enabled

Setting 26: 53.2V

Setting 27: 53.2V

Setting 29: 45.5V

Setting 31: Enabled

Setting 32: Auto

 

Any help will be greatly appreciated. As a precaution, I have handed both inverters in for testing and should have them back by the end of the week. Just hope it is not the battery bank.

 

Thanks

[Coulomb]

I don't have your particular model's firmware to read, but in other Axperts, the effective battery overcharge voltage (which triggers fault code 03 (error code 03)) is the bulk/absorb voltage plus 4.0 V (for a 48 V system). So in your case, it would be 57.2 V. [ Edit: it's probably either 60.0 V or 66.0 V, the latter for 64 V models. ]

7 hours ago, Louis0852 said:

should have them back by the end of the week.

It would be good to see what the actual battery voltage is when this happens. Or perhaps you can pull that out of logs or graphs.

Edited August 11, 2019 by Coulomb

[Louis0852]

1 hour ago, DaveSA said:

If they were sent back to Mecer/Mustek,  the problem is they have no proper test facility - either PV or batteries (or technicians!). They cannot simulate your problem and simply tell you it has been tested and works fine. The charge controllers are not properly limiting the voltage and current surges. It creates various issues depending on how the systems are utilized. As you rightly say, if batteries are full or there is surplus PV it causes havoc. the Inverter may settle down after "dipping" the PV a few times and supply only what is required or do a total disconnect - also prevalent on parallel installations.

Hi Dave. So what would your suggestion be to permanently solve the problem? I am far away from the property most of the time, and going back just to have the system off for a week or two would not be nice. Can another more reliable inverter or inverter/charger combo be better in this situation without getting rid of the batteries?

[Louis0852]

15 hours ago, Coulomb said:

I don't have your particular model's firmware to read, but in other Axperts, the effective battery overcharge voltage (which triggers fault code 03 (error code 03)) is the bulk/absorb voltage plus 4.0 V (for a 48 V system). So in your case, it would be 57.2 V. [ Edit: it's probably either 60.0 V or 66.0 V, the latter for 64 V models. ]

It would be good to see what the actual battery voltage is when this happens. Or perhaps you can pull that out of logs or graphs.

Thank you Coulomb. I will try to pull up the data in this week and post it here. As I mentioned to Dave. Do you have any suggestions with regards to a better setup or is this set of inverters up for the job?

Thanks

[Brian J]

On 2019/08/11 at 5:54 PM, DaveSA said:

If they were sent back to Mecer/Mustek,  the problem is they have no proper test facility - either PV or batteries (or technicians!). They cannot simulate your problem and simply tell you it has been tested and works fine. The charge controllers are not properly limiting the voltage and current surges. It creates various issues depending on how the systems are utilized. As you rightly say, if batteries are full or there is surplus PV it causes havoc. the Inverter may settle down after "dipping" the PV a few times and supply only what is required or do a total disconnect - also prevalent on parallel installations.

Louis have had any positive feedback from Mustek with regards to error 03. Battling with the same issue inverter works well with utility charging but once you connect PV batty voltage goes up to 67vdc on no load or float charging. Stabilizes only on 50% load with pv.

[DirkBal]

I had the same problem with a Infisolar V series, dropped bulk charge to 52.8V and float to 52.2V and have had no recurrence of the problem.

Hope this helps you too.

 

[Louis0852]

2 hours ago, DirkBal said:

I had the same problem with a Infisolar V series, dropped bulk charge to 52.8V and float to 52.2V and have had no recurrence of the problem.

Hope this helps you too.

 

Hi Dirk. Thank you for the reply. Did you also run with the pylontech batteries?

[Louis0852]

Hi Guys. So I have come across the following a dont know how any of you who are well versed with the Victron products feel about it?

 

https://www.victronenergy.com/live/battery_compatibility:pylontech_phantom

 

What I was thinking was to move away from the Mecer products and perhaps try out the Victron setup. They say in the document that the R&D departments from both Victron & Pylontech approve the compatibility. Any advise in this regard will help alot. 

 

Thank you in advance

[DirkBal]

2 hours ago, Louis0852 said:

Hi Dirk. Thank you for the reply. Did you also run with the pylontech batteries?

Yes, I have 4.  my batteries now charge to 99%, the problem is when they get to 100% the BMS steps in and stops drawing current so the

voltage overshoots.

Just my theory but has worked for more than 2 months now.

 

[Louis0852]

2 hours ago, DirkBal said:

Yes, I have 4.  my batteries now charge to 99%, the problem is when they get to 100% the BMS steps in and stops drawing current so the

voltage overshoots.

Just my theory but has worked for more than 2 months now.

 

Thanks Dirk. Do you also use the Centurion Solar monitoring?

[DirkBal]

3 hours ago, Louis0852 said:

Thanks Dirk. Do you also use the Centurion Solar monitoring?

No I don't, wrote my own, long story... but have full monitering including the Pylontechs.

Borland C++ old timer....

 

[sammy]

HI Louis,

 

I also use ICC supplied by Centurion Solar, and I have also experienced an over-voltage situation as soon as the batteries reach 100%.  I tested this with and without the monitoring, and it seems to be at hardware level, but with the monitoring system I can see it happening, so that's when I also decided to bring down the bulk and float voltages slightly.  I did this by "downtuning" 0.1V at a time, and by the time I got to 53.0V for bulk things started behaving, and still go to 100% most days but without the overvoltage and subsequent error shown on the battery. I set the float voltage 0.1V lower at 52.9V, very close to what Dirk did as well.

 

Try that and see what voltage works for you?