How to Check and Adjust the VREF (Stepper Motor Voltage) of Your Ender 3 (Pro/V2)?

The process of configuring a 3D printer is becoming more and more user-friendly as the technology advances, with the physical interfaces of the 3D printers, 3D printer interface software, and slicer software all evolving to make 3D printing accessible for anyone regardless of their technical expertise.

On the other hand, we also can’t deny that there are still plenty of possible scenarios where you will need to dive into the more technical parts of 3D printer configuration, as there isn’t much of a way to make these parts more user-friendly to manage as it stands, especially for the hardware side of things.

Today, we will be talking about one of the more technical sides of maintaining and configuring an Ender 3, which is to check and adjust the VREF value that is responsible for determining the voltage that goes into the stepper motors, where a misconfiguration can cause problems such as overheating of the steppers or the motors skipping steps due to being underpowered.

So, how can you check and adjust the VREF of your Ender 3?

To learn the current VREF values of your Ender 3, unplug everything except the power supply from the mainboard, set your multimeter to 2V, clip the positive terminal to the potentiometer, clip the negative terminal to the ground, and power your Ender 3 up.

To adjust the VREF value, you can turn the potentiometer with a ceramic or plastic screwdriver while the multimeter is still connected, which will allow you to see the change in VREF in real-time.

In the upcoming sections, we will further examine the processes of checking the VREF of an Ender 3, discuss how to adjust the VREF value, and take a quick look at the optimal VREF values that the Ender 3 should be configured to for printing optimally.

How to Check the VREF (Stepper Motor Voltage) of Your Ender 3 (Pro/V2)?

Taking a reading of the VREF value is the first step in ensuring that it’s configured correctly for the stepper motor to operate optimally, which we especially recommend performing if the extruder motors are showing signs such as skipping steps or overheating.

Here is a detailed step-by-step guide you can follow to measure the VREF values of your Ender 3:

  1. Turn your Ender 3 off and disconnect the power supply from the outlet.
  2. Unscrew the bottom cover to reveal the mainboard.
  3. Remove all the wires that go into the mainboard except the power supply.
  4. Re-connect the power supply, and turn your Ender 3 back on.
  5. Set your multimeter to 2V.
  6. Carefully connect the negative terminal of your multimeter to the ground pin (labeled with a minus sign, see the mainboard diagram for reference) of the mainboard.
  7. Carefully connect the positive terminal of the multimeter to the potentiometer (labeled as RP1, RP2, RP3, and RP4, with each number belonging to a separate stepper driver, see the mainboard diagram for reference) of the stepper driver you would like to measure.
  8. Read the value on the multimeter screen, which is the VREF value for the particular stepper driver you are measuring.
  9. Repeat steps 7 and 8 for the rest of the stepper drivers.

It’s vital to be extremely careful during the process of measuring the VREF values of your Ender 3, as the hook clips (or the probes, which we don’t recommend using due to the increased margin of error) coming into contact with the wrong pins can cause a short circuit and permanently damage your Ender 3.

How to Adjust the VREF (Stepper Motor Voltage) of Your Ender 3 (Pro/V2)?

While adjusting the VREF is a pretty straightforward process, especially if you have some experience with electrical components, it’s also one that requires a decent amount of focus and care to avoid mistakes that could lead to damage.

To adjust the VREF values of your Ender 3’s stepper drivers, all you need to do is rotate the potentiometer (RP1, RP2, RP3, or RP4) that belongs to the stepper driver you would like to adjust the VREF value for with a ceramic or plastic screwdriver.

For best results and safety, we highly recommend adjusting the VREF value very slowly and with the multimeter still connected, allowing you to see the change in the VREF value in real-time and fine-tune the value accordingly without the danger of increasing it way too much.

If you don’t have access to a plastic or ceramic screwdriver and don’t have the time to obtain one either, you will need to cut the power off before you adjust the VREF by turning the potentiometer, as touching the potentiometer with a metal screwdriver while it’s powered on can cause permanent damage to the mainboard of your Ender 3.

What Is the Optimal VREF (Stepper Motor Voltage) Value for the Ender 3 (Pro/V2)?

As the optimal VREF value depends on the stepper motor drivers and the stepper motors of your Ender 3, it’s critical to ensure that you have the correct values at hand before moving forward with performing the necessary adjustments.

To calculate the optimal VREF value for your Ender 3, the first thing you will need to do is find out which stepper driver your version of Ender 3 has, as Ender 3’s can be shipped with A4988, HR4988, TMC2208, TMC2009, and TMC2225 drivers.

To identify the stepper driver, expose the mainboard by unscrewing the bottom cover and looking at the letter written on the SD card reader, which is the piece of information that tells us the stepper driver type.

Below is the list of letters you can find on the SD card reader and the stepper drivers they correspond to:

A – TMC2208

B – TMC2209

C – HR4988

E – A4988

H – TMC2225

After you find out the model of the stepper drivers your Ender 3 came with, the next course of action is to find the documentation for the stepper driver, which includes the formula for calculating the VREF value, as each stepper driver requires a different formula.

Next up, we will need to find the Rsense value written on the sense resistors between the stepper motor connector and the stepper drivers and note the value down.

Finally, the last piece of information we require is the nominal and maximum current values for the stepper motors of your Ender 3, and we are ready to go.

Once we have the formula and the stepper motor current values, all that’s left is to do the calculation, which we will show with an example. 

For the purposes of this example, we will be using the formula for the TMC2225 stepper driver and assume that we are working with a standard Creality 42-34 motor used for the X, Y, and Z axes of the Ender 3, with a Rsense value of 150 (would be labeled as R150).

TMC2225 VREF Formula -> I/sqrt(2) = (325mV / (Rsense + 30𝑚Ω)) * (1/sqrt(2)) * (VREF/2.5V)

Creality 42-34 Current Values (I) -> 0.8A (Nominal) / 0.84A (Maximum)

Rsense -> 150

Now that we have everything we need, we can solve the formula for nominal and maximum VREF by using the nominal and maximum current values, which would give us the figures below:

Nominal VREF -> 1.10V

Maximum VREF -> 1.16V

Please ensure that you use the correct formula corresponding to the stepper drivers on your Ender 3 to refrain from permanently damaging the mainboard.

Wrapping Up

Ensuring that the VREF values of your Ender 3 are correct is vital for a healthy printing process, as the voltage that goes into the stepper motor directly impacts how optimally it performs its movements and how consistent the extrusion is as a result.

To quickly recap, to measure the VREF, start by taking the necessary safety measures by turning your Ender 3 off and disconnecting all cables connected to the mainboard except power. 

After that’s done, turn your Ender 3 back on, set your multimeter to 2V, connect the positive terminal to the potentiometer you would like to measure, and finally, connect the negative terminal to the ground, which will give you the VREF value.

To perform adjustments to the VREF values, carefully turn the potentiometers using a ceramic or plastic screwdriver and with the multimeter attached, and you will be through with the process in no time.

Happy printing!