MidNite Solar Classic 250 Charge Controller Troubleshooting

midnite solar how to and troubleshooting guides

Midnite Solar Classic charge controllers have many useful features including arc-fault detection and Ground Fault Protection (GFP) which eliminates the need for a separate GFP breaker assembly. For issues with this charge controller, it helps to troubleshoot the problem first before contacting customer service. Here is an easy-to-follow troubleshooting guide for common Midnite Solar Classic 250 charge controller issues you can use.

How to Wire Your Midnite Solar Classic Charge Controller

Before working on the wiring in the Midnite Classic always make sure all source and battery circuits are de-energized and wait 5 minutes.

The Classic has two common neutral (negative) terminals. Therefore, only one neutral conductor is required to run from the E-panel and terminate on either (or both) common neutral terminal. You should size this negative conductor to match the battery + cable. The positive DC source wire goes to the PV+ Turbine+ screw. The positive battery DC wire goes to the battery + terminal. Torque terminal screws to the specs below.

Maximum and minimum wire size

  • The Classic’s blue DC terminal connector will accept wire from #14 to #4 AWG( USE THHN; #4 AWG welding cable will not easily fit into the terminal block)
  • The Classic’s AUX 1 and AUX 2 terminal connectors will accept wire up to #18 AWG.

To connect the wiring to your Midnite Classic, follow these instructions:

  • Ensure the DC source and battery are disconnected
  • Connect a grounding conductor between the Classic and system ground
  • Ensure the breaker between the battery and Classic meets UL489 standards.
  • Ensure the breaker between the DC source and Classic meets UL1077 standards.
  • Connect the DC source and battery wire to the Classic
  • Connect any communication cables or auxiliary input/output wires
  • Torque terminal connector screws to the specifications below

The Torque specifications on the DC terminal connector (big blue terminal connector) are:

  • Up to #10 AWG toque to 25-35 inch pounds.
  • #8 AWG torque to 30-40 inch pounds.
  • #6 AWG or above, torque to 40-50 inch pounds.

Run the network cables, USB cable, BTS cable, and auxiliary input/output cables in a different conduit to preserve their signal. When installing the Classic in a MidNite E-panel, running all wiring through the same knockout hole is acceptable. It is legal to run signal and power wires together as long as all wiring is listed for the highest voltage to be encountered. Follow all local codes.

Long distance wire runs

If you are faced with longer than normal wire runs between the DC source and the Classic, the Classic comes in 3 input ranges allowing you to design DC source at a higher voltage. For example if you have a 300 ft run from a PV array to the charge controller, you can wire for an open circuit voltage close to 250 VDC accounting for the coldest temperature you will encounter. This allows you to run a smaller gauge wire than with a lower voltage charge controller. It is a crucial factor when choosing a solar charge controller.

If the wire size between the DC source and the Classic is larger than the Classic’s DC terminal connector, you can use a splicer block or similar connector to reduce down to #4 AWG close to the Classic. The MidNite E-panels are supplied with a PV input bus bar that accepts up to 2/0 wire.

How to Program Your MidNite Solar Classic Solar Charge Controller (for flooded lead battery, sealed lead battery, and lithium-ion battery)

Commissioning the Classing (Quick Start)

The Classic will enter the Quick Set screen upon initial power-up. If it does not enter the Quick Set or you want to restore to factory default, follow these steps to initiate a Quick Set:

  1. With the power off to the Classic, hold the LEFT and RIGHT arrow keys down.
  2. Power the on the Classic, continue holding arrow keys until the setup screen is displayed.
  3. Answer the questions on the next several screens to complete Quick Set.

MNGP programming

To access and modify on the integrated Midnite Graphics Panel (MNGP):

  • Navigate using the LEFT and RIGHT arrow keys.
  • Press ENTER to go into that menu.
  • The MAIN MENU key also backs you out of any submenu.
  • Use the soft-keys for options and views.
  • Press ENTER to save changes before backing out of any menu/submenu.

To set up contrast, backlight, and volume:

  1. Depress the MAIN MENU key.
  2. Scroll left or right to highlight MISC and depress the ENTER key.
  3. Use the LEFT and RIGHT ARROW keys to select the feature to set, depress the ENTER key.
  4. Depress the UP and DOWN ARROW keys to adjust; depress ENTER to save.

To set the current limit set point:

  • Depress the MAIN MENU key.
  • Highlight the CHARGE menu and depress the ENTER key.
  • Scroll to LIMITS and depress ENTER.
  • Depress the RIGHT ARROW key to highlight “Output Amps” or “Input Amps” column.
  • Use UP and DOWN ARROW key to change the current limit; depress ENTER to save this data.

Calibrating Battery and PV voltage

To calibrate the Classic battery and PV voltage readings, you will need an accurate and calibrated voltmeter to check the actual bank voltage or input PV voltage. Using the voltmeter, measure the voltage on the DC terminal connector of the Classic and compare this reading on the MNGP in the TWEAKS menu. To adjust the reading of the Classic to the reading on the voltmeter, follow these steps:

  1. Depress MAIN MENU, scroll to TWEAKS, depress ENTER.
  2. Highlight VBatt and use the UP and DOWN ARROW keys to match both readings.
  3. Depress ENTER to save.

Configuring DC input source

To select the Classic’s mode of operation, follow these steps:

  1. Depress the MAIN MENU key.
  2. Scroll left or right until MODE is highlighted, depress ENTER.
  3. Scroll to the right and highlight the correct mode, then use the UP and DOWN ARROW keys to set the mode you want.
  4. Take note of the RIGHT SOFT key- most modes have set points that can be adjusted.
  5. Depress MAIN MENU until you get back to the MODE menu.
  6. Set the ON/OFF to ON and depress ENTER.


To initiate a manual equalization charge;

  • Go into the CHARGE menu and highlight EQ, then depress the ENTER key.
  • “EQ Stopped” will be highlighted. Depress UP ARROW key to select “EQ Started”. Depress the STATUS key to return to the home screen.
  • To stop a manual EQ in progress, simply reverse the steps above.
  • Set the EQ Timer (Charge/ChgTime) for the amount of time you want to EQ.

Note that you should only use equalization if you have a flooded lead-acid battery bank in your RV or off-grid home. Floating other types of batteries could ruin them.

To set up Auto E;

  • Go into the CHARGE menu and highlight EQ, then depress ENTER.
  • Now depress the SOFT RIGHT key labeled “AUTO EQ”. This enters the AUTO EQ setup menu screen.
  • The left side of the EQ setup menu will show the number of days, or “interval” between auto EQ charge cycles. If set to zero, it will display MANUAL, which is the same thing as DISABLED.
  • On the right side of the AUTO EQ setup menu is the number of DAYS that the AUTO EQ will retry if it does not finish the number of hours and minutes the Classic has been programmed to EQ for during the first day.

How to Update Firmware on Your MidNite Solar Classic Charge Controller

You can update the MidNite Classic firmware using a standard USB cable and a Windows-based PC. Please see www.midnitesolar.com and click on the software tab for the firmware and instructions.

To prepare your Classic charge controller for update:

  1. Go to your electrical panel and identify the input and output breakers for the Classic. Turn them off. Wait 3 minutes for the Classic to de-energize.
  2. Remove the four screws holding the front cover of the charge controller. Do not let the front cover hang by the cable.
  3. Holding the front cover with one hand place a screw in the top left hole of the front cover and screw it into the top right hole of the black casting.
  4. Use any standard to Mini B USB cable to connect the Classic to the PC. The smaller terminal connects the USB port on the Classic. The USB port is found on the right side of the Ethernet Jack in the lower part of the Classic.

The Firmware upgrade is fail safe so if the wrong code is installed the Classic simply says “Wrong Code” prompting you to load the correct code. Also if the upload is interrupted for whatever reason simply start over.

Why are All the Fans on My MidNite Classic Running even on Resting Mode?

If the fans run even on Resting mode, check to ensure the Turbofan wire is not pinched at the top by the front cover.

How to Factory Reset a MidNite Solar Classic 250

Note that performing a factory reset on the Classic will erase all settings.

To do a software factory reset, follow the instructions below:

  • Turn the PV breaker and battery breaker off (if you don’t have a breaker, get one) and make sure the display has gone dark.
  • Hold the left and right arrow keys and turn on just the battery breaker. Continue to hold the arrow keys until you see the Quick Start Menu.
  • Follow the on-screen prompts to setup your controller.

You must get the battery charging voltages from the battery manufacturer. This is very important and do not just leave it at the default settings, as it is likely this will undercharge and slowly destroy your batteries.

To do a hardware factory restore, follow these instructions:

  • Turn the PV breaker and battery breaker off (if you don’t have a breaker, get one) and make sure the display has gone dark.

Do a hardware factory restore. There are 3 jumpers directly above the blue terminal block. For instructional purposes we will call the Jumper at the most left JP1 and the rightmost JP4 (labeled “Boot”).

  • Step 1- Turn the PV and battery power off to the Classic and remove the front cover.
  • Step 2- Locate and remove the two jumpers JP1 and JP4; hold the jumpers in your hand.
  • Step 3- Turn the battery power on to the Classic.
  • Step 4- Within 1 minute, place the jumper JP4 on its two pins and then place jumper JP1 ON its two pins. At this point the 3 LEDS on the top of the circuit board should flash back and forth for about 45 seconds.
  • Step 5- After the flashing stops, power down the Classic and remove jumper JP1 and JP4 and stow them back on a single pin like they were.
  • Step 6- Put the front cover on and power up the Classic. If you have custom settings you will need to use your MNGP or Local APP and reset the battery voltage, set points, and any AUX functions that were in use will need to be re-selected and programmed.

How to Set the Date and Time on a Midnite Solar Classic

To set the time and date manually on the Midnite Solar Classic follow the steps below:

  1. Push the Main Menu button repeatedly until “Charge” is highlighted.
  2. Scroll left or right to highlight “MISC” and push the “Enter” button
  3. Scroll to “Time” and push “Enter”
  4. Now scroll left or right to highlight the data you want to manually change. Use the up and down buttons to change the data.
  5. When you have all the data changed push the “Enter” button to save the changes.

How to Hook Up Two MidNite Solar Classic in a Master Slave Mode

When classics are connected together using Follow-Me cables you get the following features:

  1. MODE coordination. All will follow for BULK, EQUALIZATION and FLOAT.
  2. Battery Temperature Sensor (BTS) sharing. Pick a Classic to install the BTS in, it can now be called “BTS MASTER”.

Note that there is no other designation of “Master” or “Slave” with the F-Me network, all classics can switch modes and send data around the network.

Follow these installation suggestions:

  • Pick one Classic to be the BTS MASTER. Set in TWEAKS to BTS NET= MASTER and all others to BTS FOLLOW. Install a BTS in this Classic only.
  • If using a Whizbang JR install in this Classic. Note that SOC% and other WBjr info is not shared with other Classics.
  • Set BTS MASTER Classic Absorb time to what you need, set the other to 10 minutes longer.
  • If using REBULK set it in the BTS MASTER Classic only.

The Blue LED at the top of the Classic Circuit board will flash to indicate Follow-Me network operation. 1 flash means no data, no cable or F-Me not turned on in TWEAKS. 1/10th second blink means data is okay. To test a F-Me cable, connect in a Classic looping the middle jack to the bottom jack. If the cable is good and the Classic is working in the F-Me the Blue LED will go from 1-second blink to 1/10th second.

Why is My MidNite Classic Not Reading the Right Temperature?

The Classic comes with a battery temperature sensor (BTS). This sensor raises or lowers charge voltages based on the temperatures. If the BTS is disconnected or shorted the Classic will automatically default to 25 C.

How to Adjust Current Limit in My MidNite Classic Solar Classic

The Midnite Solar Classic has a current limit component that interacts with the temperature of the charge controller. If the Classic is exposed to extremely hot ambient conditions the output current will be reduced automatically to protect the charge controller. If the orange LED is on in the MNGP, it indicates that the charge controller is in current limit mode.

If the charge controller is not hot and the orange LED is on, most likely the current limits setpoint is too low. To check this, follow these steps:

  1. Press Main Menu
  2. Highlight the CHARGE menu and press the “Enter” button
  3. Scroll to “LIMITS” and press the “Enter” button
  4. Press the right arrow key to highlight the “Out Amps” column
  5. Use the up and down arrow keys to change the current limit then press the “Enter” button to save this data.

How to Use the Onboard DC GFC (Ground Fault Protection) –Enabling and Disabling

The Classic has internal ground fault protection (GFP) built in. This eliminates the need to purchase and install an external DC-GFP.  The Ground Fault device detects a fault between battery/PV negative and earth ground just like the breaker DC-GFP system, but with the Classic it turns off the charge ability and sounds a loud warning when a ground fault is detected. The Classic will restore charging when the fault is cleared.

To disable the internal Ground Fault Protection, you need to remove the jumper labeled GFP and disable the GFP function in the TWEAKS menu by following these steps:

  1. Press Main Menu
  2. Scroll to the right or left until “TWEAKS” is highlighted and press “ENTER”
  3. In the “TWEAKS” press the right soft key to get to the MORE menu
  4. In “MORE” scroll until GFP is highlighted
  5. Use the up and down arrow keys to toggle between on and off
  6. Press ENTER to save

To reset the internal GFP function after detection has occurred:

  • Fix the actual ground fault, then turn OFF the Classic and turn it back ON. Do this by turning the external battery breaker to OFF position and then to ON position.

How to Use a Midnite Solar Classic with a Wind Turbine

AUX 2 needs to be programmed for the Classic to work with the clipper:

  • Enter the MAIN MENU and scroll to AUX, then depress the ENTER key.
  • Scroll to the right to highlight the text under AUX 2 and depress the RIGHT SOFT key.
  • Scroll up or down to find Clipper Control and depress the RIGHT SOFT key again.
  • On this screen, select either AC or DC to match the Clipper being used (AC is the default).
  • Depress the RIGHT SOFT key again, and set the absolute maximum voltage you want the Clipper to allow before clipping occurs.
  • Depress ENTER to save this data.
  • Depress MAIN MENU until you get back to AUX 1 and AUX 2 screens.
  • Set the text under AUX 2 to read Clipper Control, depress ENTER.
  • Press STATUS to return to the home screen.

You will need to select a power curve from the list of pre-loaded curves or build your own. You can access the list of power curves by following these steps:

  1. Push the Main Menu button.
  2. Scroll to the left or right until “Mode” is highlighted and push the “Enter” button.
  3. Set the status to OFF and then use the right soft key to select “Graph”.
  4. Using the left soft key select “MEM”. Now you can scroll up and down through the menu and select the curve that was designed for your turbine.
  5. Once you find the correct power curve use the right soft key to select “RECALL”. Now push the “Enter” button to save this power curve to the Classic’s memory.

There are also 9 memory spaces to save a custom power curve. To build custom curves:

  • Select a memory location between 1 and 9 and hit “RECALL”.
  • Use the right and left arrow buttons to scroll through the 16 steps in the custom curve. On each step, you can set the amperage by pressing the up and down buttons.
  • When you have the power curve the way you want it, select “MEM”.
  • Use the up and down buttons to select a location 2 through 9 to save it in and select “SAVE”.
  • Now push the “Enter” button to save it to the Classic’s memory.

You can use the MidNite Local Application software to program the wind curve and make real-time adjustments to the curve while your turbine is operating. You can download the Local Application from the MidNite website, www.midnitesolar.com under Software.

MidNite Solar Display Shows Wrong Voltage, Wattage or Amp Readings

If Classic is not making the same amount of wattage as you have for solar panels:

  • First you should note that a solar panel is rated in a lab so in the real world we typically see about 80% of what it is labeled (i.e 100W Panel becomes an 80W panel).
  • Does the Classic say Absorb, Float, or EQ? If so, that means the battery is nearly full and the Classic is throttling back to prevent over charging the battery.

If the state of charge seems inaccurate:

  • Verify the neutral temperature for the temp comp is set per the battery manufacturer’s specifications.
  • Verify the Amp Hours of the battery bank are set properly. Note that batteries in a string do not add in amp-hours. If you have a single string of 8 batteries, each having 220Ah, then you have 220Ah of capacity. If you have 2 such strings, then your bank has 440Ah of capacity.
  • Verify the efficiency of the battery is set properly according to the battery manufacturer’s specifications (typically 86% for flooded, 90 % for sealed batteries).

Check this too: Berkey Water Filter Troubleshooting & How-to Guide

If the solar charge controller switches between Resting and Bulk MPPT repeatedly but produces 0 watts:

  • This can be normal during low light conditions.
  • Watch the IN voltage and see if it is setting stable and does not change when the charge controller goes from Resting to Bulk MPPT. If so call customer service.
  • Watch the IN voltage and see if it slowly drops to battery voltage (or close) when the charge controller goes to Bulk MPPT. If so this is usually a sign of a High resistance connection (the loose connection between the solar charge controller and DC source).

If the display shows 0 volts in (or real close) but the battery voltage looks correct:

  • If this is a new installation or you recently altered the installation check for reverse polarity on the DC input of the solar charge controller.
  • If this happened out of the blue or you have eliminated reverse polarity as the issue call Midnite customer service.