Classic 150 still seeing 11volts on input with panels off

[estimaman]

I am using a classic 150 with solar panels and noticed that I am still seeing 11 volts on the input side at night with the panels removed and isolated, also the SPD on the input side is still lit up and seeing a voltage. Output is reading 25volts (24volt battery bank) my concern is that I thought there was no reverse voltage with this controller.

[Halfcrazy]

There will be a slight residual voltage as you see. There is no current to speak of though. This is very typical of any MPPT controller and it has to do with the circuitry that tells it when it is ok to turn on.

Ryan

[boB]

Output is reading 25volts (24volt battery bank) my concern is that I thought there was no reverse voltage with this controller.

The voltage you see on the input terminals comes from a resistor across the relay contacts.

This resistor is there for various reasons but it tends to charge up the input capacitors to around
half the battery voltage if you have nothing connected (PV) to the input terminals as you noticed.

When you say "reverse voltage", these types of controllers (Not just the Classic) do create a
voltage on the input terminals when operating that you read on the meter...  So, in that
respect, the controller can actually supply some current into the input circuit if that
circuit "draws" anything on the input although the Classic will shut off if it goes
over a few amps.

boB

[estimaman]

Thanks guys for the quick and thorough response.