Input Voltage Dropping When MPPT is turned On

[elijahq]

Currently have 4 - 290watt panels in 2 series of 2 and brought back to the combiner box - MNPV3, 2 15A breakers in the combiner and the combiner running to the classic 150, the classic 150 is then running to a bus bar that ties in 2 series of 6v batteries - in a 24v configuration.  The issue that I am running into is that when we turn MPPT Mode on, the input voltage drops from 70v to 27v, troubleshooting has consisted of bypassing the combiner box, rewiring the panels from series to parallel, removing 1 string of batteries at a time, and changing the charge controller, this setup is for a remote communications site and I currently operate 40 other sites using an identical setup and have never seen this issue before.  It started randomly 2 days ago and we have not been able to figure out why it is doing it, any help or insight would be greatly appreciated.

[ClassicCrazy]

Is it a Classic Charge controller ? 
Can you get a screen capture of the Local Status app so it shows all that is going on ?
Did you short circuit test the PV panels ?

Larry

[FNG]

This is odd, it sounds like you have swapped or eliminated everything except the pv modules. I agree with ClassicCrazy I would do some I&V curve testing on those modules

[elijahq]

Is it a Classic Charge controller ?
Can you get a screen capture of the Local Status app so it shows all that is going on ?
Did you short circuit test the PV panels ?

Yes it is a Classic 150

We did not short circuit test the panels, mainly because we isolated the panels individually and saw the same thing happen.

[bee88man]

Could this simply be a result of battery fault...

[boB]

Maybe you could take a short video with your phone of what the Classic screen is doing ?