DIY Manual

55 | P a g e 10-543-1 REV A
DIY Manual
Is the IN voltage 0 on the MNGP? If so check for reverse polarity on the PV input to the Classic.
Battery Over-voltage
Ensure the Battery voltage is below the Absorb and Float voltage setpoints. If not, do you have
another charging source (2
nd
solar, wind, inverter-charger, or generator) on your battery bank?
If so, turn it off until you finish troubleshooting the Classic.
Go to the 6
th
Status page; you will read CLASSIC XXX (i.e., CLASSIC 150) at the top left of the MNGP
display. In the upper right corner, you will see XXV BAT (i.e., 12V BAT). Is this voltage correct for
your battery bank? If not, perform a soft factory reset (VMM, instructions in this Manual).
During initial Classic set-up, one of the steps is to recognize the battery bank nominal voltage
(i.e., 12V, 24V, 48V). If you accepted the wrong bank voltage and set the charge voltages, the
Classic will show an over-voltage condition. For example, if you accepted the bank voltage as
12V then programmed in the Absorb charge voltage at 29.6V, you will get an OV condition.
Disappearing PV IN Voltage
Disconnect the PV wires from the Classic’s input terminal block. Using a multimeter, measure
the PV voltage directly from the PV wires. Is voltage present? If not, see PV INPUT ISSUE section
above. If voltage is present, reconnect the PV wires to the Classic’s terminal block. Be mindful
of polarity and always turn off circuit breakers before connecting or disconnecting any wires.
With the PV wires connected, does the IN voltage drop to zero or near zero volts? If so, the
Classic is defective. Call MidNite’s Tech Support for further assistance.
Classic Makes No Power: Bulk-to-Resting
Does your MNGP show the Classic switching between Bulk and Resting? This means the Classic
is trying to make power, has sufficient PV input voltage, goes in to the Bulk charging mode, then
very quickly switches to Resting. You may hear an internal relay click.
1. If PV IN voltage drops to battery voltage or close to it, the problem is probably a bad PV
connection.
2. If PV IN voltage remains the same or at a normal level, the Classic has probably lost its FET
drive.
3. If the PV IN voltage is normal and the Classic stays in Bulk or shows Bulk-to-Resting yet
makes no power, you may have a bad resistor - R145. Repair of unit at our factory is
required.
NOTE: With the PV wires disconnected from the Classic or the PV input circuit breaker turned
off, does the MNGP show some IN voltage? If yes, this is a good thing. The Classic has a 10K
ohm resistor across the BATT POS and PV POS terminals. This resistor pre-charges the PV
input capacitors up to about 2/3rd battery voltage, which is the IN voltage you are seeing. If
you see 0V, that is a bad thing. The Classic needs repair.