midnite classic creating 117V at pv input

[australsolarier]

http://kb1uas.com/mnsforum/index.php?topic=2753.0

not according to this.

[ClassicCrazy]

unless there is something new - Windows 10 doesn't work for firmware updates. I tried.
Ryan said they were working on something new that will work with Windows 10 .

Larry

[Vic]

This may not be on target ...   

But about seven years ago,  was running an Outback MX-60 MPPT CC,  and it developed the capability of making "power from darkness";

The MX said that it was delivering about 50 - 60 watts output,  the Vin was about 10 volts above Vbat,  the MX was warm,  and its fan would run periodically.

Returned it to OB,  and the Repair Report was that there were some leaky FETs.

But,  the above may well have nothing to do with this situation.   FWIW,  Vic

[australsolarier]

HELLO AGAIN
being of an inquisitive mind, i charged the lifepo4 battery again just a few minutes ago. (this time with the permanent wiring) it went into float.
aha!
it said float on the display, the midnite used 0.7amps and?? you guessed it, the 117 volts at the input. turned off breaker to the solar panels, the 117v stayed. i waited a few minutes just to make sure. then disconnected the battery and restarted the midnite. now in resting mode.

for the unbelieving thomasses i took some pictures of the midnite status panel and the display.
after midnite blokes are ready with the simplified update i will do more tests.

i haven't actually checked the other midnite in 12 volt configuration if it is doing the same thing. as there is a converter connected to it, pulling down the battery voltage might trigger the midnite to come out of his "rebellious state".

interesting to say the least.

greetings urs

[dgd]

aha!
it said float on the display, the midnite used 0.7amps and?? you guessed it, the 117 volts at the input. turned off breaker to the solar panels, the 117v stayed. i waited a few minutes just to make sure. then disconnected the battery and restarted the midnite. now in resting mode.

Why is this a surprise to you?
When the controller moves from Absorb to Float the current required from the PVs reduces as the controller now only needs to maintain the Float voltage.
So the voltage from the PVs increases up to near the PVs open circuit voltage (117v in your case).
This is absolutely normal.
There is no need to disconnect the PVs as the controller is working normally, its preventing the batteries over charging.

And the 117v on input after you disconnect the PVs...  have you considered the Classic's PV input capacitors?

dgd

[australsolarier]

dgd,
you absolutely missed the point of this thread.

IT IS ABOUT THE MIDNITE CLASSIC REVERSING

ACTUALLY CREATING 117V FROM THE 52 VOLT BATTERY.

now i repeat this here for you: it is not about disconnecting the panels because i am worried the midnite is not doing the right thing in float.
it is about, when you disconnect the panels after float, that the midnite keeps outputting 117v for hours on time without any panels connected at all
is it too much asked for you to read the whole thread?

and as described above:
THE LATEST UPDATE IS SUPPOSED TO REMEDY THIS INTERESTING FACT.

[dgd]

Australsolarier,

I have absolutely NOT missed the point of this thread.
That somehow the Classic has a voltage boost function operating in the direction from battery output stage to the PV input stage is, for me, just incredible. Such a feature has never been mentioned by the designers of the Classic but if this is a secret feature then I look forward to the designers explanation of its purpose.

You appear yo have reached this conclusion based on a few watts of battery power being consumed by the Classic and the PV input reporting 117v even though the PVs are disconnected.  I can't follow your logic in how you have come to this conclusion.

I would hazard an explanation for what you see as below.
That 117v you see is really suspiciously identical to the PVs near OCV.
Even when you disconnect the PVs then the Classics input stage caps will remain charged at 117v (they are, I guess, several thousand uF at 200v), they are probably discharging very very slowly if there is no output current going from Classic to battery bank.
Hence you see the 117volts for some time after the PV input is disconnected.
Perfectly normal, no problems.

The WBjr current into the Classic will be different from cool and resting when compared to hot and just come off Absorb to Float. Hot electronics consume more energy and if the fans are activated to provide cooling then more current ill be used.
The 0.1 amp to 0.4 amp range you originally posted again is completely normal for resting AND DOES NOT mean the Classic is operating in some weird reverse voltage boosting mode to show the 117volt input reading you see.

dgd

PS  when you see 117v input that does not mean there is 117 volts being output by the classic to your batteries
      The true output voltage is the battery voltage you see on the Classic's display

      And I will bet the firmware upgrade you mention is not fixing any reverse voltage boost
      Its probably just timing out a FLOAT with zero current output and reverting to RESTING mode

[Halfcrazy]

So the classic will go either way 

We use it in boost mode in burn in to feed its neighbor, There is also a couple hidden modes (Well semi hidden) for using it in boost.

Basically (I don't understand the software/hardware reason) with a Asynchronous rectifier (I think I got that right) any time the output of the classic sees the voltage above the target it tries to go the other way. Of course we have reverse current limits etc for that BUT if the battery is full and you disconnect the PV in a regulated state (IE Float or absorb) the Classic will basically set in that neutral state holding the PV at the last voltage it was running at. Normally if in bulk for instance there would be a sweep and it would catch it but in regulated states it does not sweep so it never finds this issue. We never had software in there to watch for low wattage only and shut down I guess, so we now have that added in there.

Ryan

[australsolarier]

halfcrazy

i really really appreciate that you take me seriously.

rather than writing half a page trying to refute my observations.

thanks thanks thanks
greetings urs

[dgd]

Nobody is refuting your observations
Just the conclusions you are coming to based on those observations
You seem to be reaching these conclusions without any evidence

Dgd

[australsolarier]

dgd,
are you trying to take the micky out of me because i am an australian?

[dgd]

No, I leave that to our rugby and cricket experts
But I'm please you see the funny side of this thread
I started laughing when I noted the use of 'bonkers' in a posting - not from me 

Dgd

[australsolarier]

ok dgd,

as you are in this nick of the world, and you need proof,

i invite you to come over to australia and observe for yourself. i pick you up at sydney airport, you may stay in my house in the spare bedroom, free food, etc. bring your own multimeter, just in case. then we can look at it together. promise not to entertain you with silly new zealand jokes. don't like them. i lived in NZ for about two years myself and liked it there.
shall we leave it at that?

[dgd]

Hi,
Thanks for the offer, however I don't dispute what you are observing on the Classic screen.
I just think there is a better explanation than saying the Classic is taking voltage from your battery and boosting it to the 117v you see on the display for input volts.

Did you not think my explanation for your observations was credible?

I think its time for me to defer to the Midnite engineering expertise who will, no doubt, resolve this.

dgd

[australsolarier]

dgd,

you are not observing anything, i am doing the observation. please read the thread again. it is all explained. multiple times.

i really do not know how to explain it more to you. i am starting to think you are just trolling.
30 watts go into the midnite from the 52 volt battery. the input shows 117 volts or thereabouts. the whizzbang jr shows -0.7 amps.  the midnite is getting warm. every so often it turns on its internal fan. the 117v remain for hours. without any solar panels connected at all. i mean, the solar panels were moved, i carried them away on the porch. disconnected. 10m away from the nearest cable.

there is only so many times i am going to explain this.
i might be australian but that does not mean i am absolutely without any minimal amount of intelligence.

if you are serious about refuting my observation, why don't you try it yourself.

i mean, i used to work in electronics, though many years ago.
i mean you can believe australia is part of new zealand ..............

i am not going to answer to you personally anymore.
now i feel a bit aggravated. sorry about it.