# MT3608 boost converter gives no output or the wrong voltage

> Fix a boost module: turn the trim pot, remember output cannot be below input, check the input polarity and keep the current within the rating.

Canonical: https://roboticsengineering.in/fix/mt3608-boost-converter-no-output-or-wrong-voltage/ | Published: 2026-11-03 | Updated: 2026-11-03

**A boost converter can only raise the voltage.** The output is always at least the input minus a small drop.

## What the message means

These small boards have a trim pot that sets the output. Many arrive set low, and the input voltage passes straight through when it is above the set value.

## Fix it in this order

1. Check the input polarity and the input voltage range of your module.
2. Turn the trim pot slowly while you watch the output with a multimeter.
3. Make sure the target output is above the input voltage.
4. Keep the load current within the rating at your input voltage, since a boost draws more input current than it delivers.
5. Use thick wires on the input and keep them short.
6. Check the module for heat.

## Why it happens

The MT3608 module is a boost converter. It can only raise the voltage, so the output cannot be lower than the input. The output is set with a small trimmer, and many modules arrive set to a low value.

Check that the input is below the voltage you want, turn the trimmer slowly while watching the output with a multimeter, set the voltage before you connect the load, and check the input current rating and polarity.

## If you see this, do this

| You see | Do this |
| --- | --- |
| Output equals input | Trim pot set too low. |
| No output | Polarity or input too low. |

## Related

[buck converter sag](https://roboticsengineering.in/fix/buck-converter-output-drops-under-load/), [set the voltage first](https://roboticsengineering.in/fix/lm2596-buck-converter-set-voltage-before-connecting/).

Last reviewed: November 2026. These are the usual causes and the order that finds them fastest. Test on your own board; clones and cables differ.