MPPT and modes getting confused

[mike90045]

Classic 200V (rev 4)   
Device ID: 4787 3270
IP: 192.168.1.105:502
Firmware:     
- Classic Rev: 1849
- Network Rev: 1839
MPPT mode : Legacy P&O

Problem:  been several days with intermittent clouds, and my controllers (Morningstar MPPT60 & Classic200) have been flailing about from bulk to absorb and back, dozens of times in an hour.  Trying to understand why my batteries are slow, I see that usually by noon, my Classic has gone numb, only outputting 200-300 watts, while my other controller is cranking away.  I'm not above using the local app to kick in an extra absorb cycle when I know conditions are deteriorating.
  But lately, I've not even been able to do that when it has gone numb.  I've had to turn the classic off for a couple seconds, and then back on, and it's good for 1,700watts for a couple more hours.  It's not a heat thing, today was just over 75°F, and it ran fine after a off/on cycle (not a reboot, just turning the MPPT mode off/on in the local app).

Ideas ?  Suggestions ?   troubleshooting thoughts ?   data files to collect ?

edit - added attachment of todays battery charging status (Combox monitor log)

[boB]

Mike, Please show the PV input voltage if you can.

Also, I can't tell what the battery voltage is although it is shown on the legend at the bottom.

I don't suppose the controller could be going to Absorb because the Morningstar controller thinks the battery V is lower ?

If so, the PV voltage input would be going high at the time of low output current.

boB

[mike90045]

Caught it acting up.   Screen shot shows other controller cranking to charge battery, Classic is in EQ mode, but is putting very little power out. Classic is aiming for about  1V higher than the other controller is set to, and on a plain, simple day, does it fine, the 2 controllers assist each other, I have the classic set to time out it's absorb shortly before the morningstar (the 2Kw array cannot Absorb the batteries and power loads at the same time, the 3Kw array on morningstar can. 

PV array (2KW classic) VOC is 161V   (ranges from 154 - 172v per season) (2nd shot)

Earlier when batteries were low and sun was bright, I see the classic can extract a nice 2.1Kw out of the 2kw array (3rd screen shot)

[boB]

When it does this (goes to zero watts at 67 volt battery), turn off the Morningstar.

I bet that the MS is just making the battery voltage higher than the Classic is doing and
the Classic is just reducing its output because of that.

Just reading a slightly different battery voltage I am thinking.

But you said the Classic was set for one.0 volts higher set point than the MS ?
What is it set for ?  68.0 volts ?  try 69.0V or 70.0 V maybe just to check this.

Also check the MAX temp comp'd voltage limit although it should go UP as you raise the
EQ or Absorb voltage above that present max setting.

The VMM is just supposed to set most settings to a known point.  Things like logs and
factory adjustments aren't changed though.

boB

[mike90045]

I've tweaked the meter calibration to match - If I power off and on the classic, it will start putting out 1200w for a while before the battery comes up to 67V (from 66V)  At that point the morningstar backs off and all is well. 

But the issue is scattered clouds.   The Classic gets confused and hangs up in some low throughput state, even at 63V when batteries are way low.   Switching from Absorb to Float to EQ does not seem to bring it back, but turning it off at the MPPT Mode does the trick.    Maybe the clouds/sun/clouds/sun overflows some buffer in the MPPT algorithm that an Off/On will reset?   My first screen shot above, has a full volt of headroom that the classic should be using (and it did a couple minuutes later when I re-started it.
Unless the comms are hanging up for minutes at a time, and the FORCE button does not work 'cause the link is bad (but it's the same link Morningstar and Combox use, and the Local App seems to be more robust than the other two) But the local app usually detects bad comms and exits to a failed connection screen.

[boB]

Another thing you can try is to press the ENTER button on the Classic MNGP panel when it is
having this problem.  That way, the Classic will only do a new sweep and you will not have
to turn it off and back on again to get it to recover.

If this is the case, then the Classic would most likely fixed itself in another 3 minutes (sweep interval) unless
you have the sweep interval set to  zero minutes. 

But the Classic ~should~  just come back to its last known MPP input voltage.
boB

[Resthome]

Another thing you can try is to press the ENTER button on the Classic MNGP panel when it is
having this problem.  That way, the Classic will only do a new sweep and you will not have
to turn it off and back on again to get it to recover.

If this is the case, then the Classic would most likely fixed itself in another 3 minutes (sweep interval) unless
you have the sweep interval set to  zero minutes. 

But the Classic ~should~  just come back to its last known MPP input voltage.
boB

I think i tried that but not sure.  And the fact the the next sweep kept on having the same results puzzled me. Just seem like it go stuck in this wrong loop. Still looking for an older occurrence of this with the same controller.

[boB]

Another thing you can try is to press the ENTER button on the Classic MNGP panel when it is
having this problem.  That way, the Classic will only do a new sweep and you will not have
to turn it off and back on again to get it to recover.

If this is the case, then the Classic would most likely fixed itself in another 3 minutes (sweep interval) unless
you have the sweep interval set to  zero minutes. 

But the Classic ~should~  just come back to its last known MPP input voltage.
boB

I think i tried that but not sure.  And the fact the the next sweep kept on having the same results puzzled me. Just seem like it go stuck in this wrong loop. Still looking for an older occurrence of this with the same controller.

Yeah, it just seems like the Classic thinks that the battery voltage is at or above the set point.  All it can do is to
go to zero output and bring the input voltage up to near Voc in order to do that.

Did it actually say BULK MPPT   or FLOAT MPPT  at the time it was a low or zero power ?  Or did the display say Absorb or EQ or Float ?

boB

[Resthome]

Another thing you can try is to press the ENTER button on the Classic MNGP panel when it is
having this problem.  That way, the Classic will only do a new sweep and you will not have
to turn it off and back on again to get it to recover.

If this is the case, then the Classic would most likely fixed itself in another 3 minutes (sweep interval) unless
you have the sweep interval set to  zero minutes. 

But the Classic ~should~  just come back to its last known MPP input voltage.
boB

I think i tried that but not sure.  And the fact the the next sweep kept on having the same results puzzled me. Just seem like it go stuck in this wrong loop. Still looking for an older occurrence of this with the same controller.

Yeah, it just seems like the Classic thinks that the battery voltage is at or above the set point.  All it can do is to
go to zero output and bring the input voltage up to near Voc in order to do that.

Did it actually say BULK MPPT   or FLOAT MPPT  at the time it was a low or zero power ?  Or did the display say Absorb or EQ or Float ?

boB

It start to show up around morning so it was definitely in Bulk MPPT. Also verified this in data. It occurs every 3 minute sweep and it stays low for exactly one minute and then goes back up and continues to repeat on every sweep. So why does it stay low for exactly one minute? I know how do we find these thing! 

[boB]

Resthome...   Are you  the same person as    mike90045   ?


I did not think so ?  Do you have a Morningstar and Classic running at 67 volts ?


Mike's button didn't work for  you ?

boB

[Resthome]

Resthome...   Are you  the same person as    mike90045   ?


I did not think so ?  Do you have a Morningstar and Classic running at 67 volts ?


Mike's button didn't work for  you ?

boB

No not Mike, just ended up posting to the wrong thread by mistake. Disregard my comments. 

[boB]

Resthome...   Are you  the same person as    mike90045   ?


I did not think so ?  Do you have a Morningstar and Classic running at 67 volts ?


Mike's button didn't work for  you ?

boB

No not Mike, just ended up posting to the wrong thread by mistake. Disregard my comments.

That's OK !  Ryan and I wondered if maybe you were pressing Mikes' button !!     

boB