Input Voltage question

[SM-Viper]

Hi all!

I've noticed on my Kid there is always some voltage on the "Input Voltage" of the status screen. Even in the middle of the night I still see about 3.7v or so. It seems to change when I toggle the PV breaker on or off. What gives? Is this normal? I was under the impression that it was to display the input voltage from the PV. Is that right?

-Thanks!

[xsnrg]

There is always radiation hitting the panels, just not enough to produce any current at night.  People with large arrays have reported measurable current from moonlight.  My 3 100w panels in series show about 8-9v overnight.

[TomW]

My Kid does this and it seems completely normal, even with the input disconnected. Leakage through the input FETS cause it, I believe.

Classics do it too.

Just saying..

Tom

[Westbranch]

check out the amps coming in...  bets on 0.1???

on PV panels Volts rises first followed by amps...  need both

[SM-Viper]

Sounds good to me. Thanks all for your replies. BTW, what is a typical setting for rebulk? I'm looking for some reference.

[Vic]

Would bet that this has nothing to do with any irradiance on the PVs at night.

All of the MPPT CCs that I have seen -- really just the OB MX-60s,  Classics and the KID.   In some it may well be a bit of FET leakage.  For the Classic,  believe that there may be a resistor that is causing the lowish Vin to be displayed ...   it has been discussed on this Forum in the past.    Just my guesses.   Vic

[Robin]

There is a resistor across the relay that allows the input voltage to be matched to the battery voltage before closing the relay. It is very high resistance so current flow is virtually zero, but you will see some voltage across this resistor on the PV side. It is not FET leakage or moonlight. It is normal. If you ever see zero there, that means the controller is fried, so don't be looking for zero!

[Westbranch]

If you ever see zero there, that means the controller is fried, so don't be looking for zero!

Thanks Robin, that is an important little know fact out here!