DIY: Upgrade Your Lithium Hot Glue Gun

If you're interested in modifying a lithium battery-powered hot glue gun, this article is worth a read.

If the switch on your FOGO lithium battery hot glue gun is broken and won't turn off, it's likely because the switch can't handle a 2A current—it just melts inside. So, what's the solution? Keep reading to find out.

First, open up the glue gun. You'll notice that the heating element inside appears to be a soft heating wire that doesn't maintain a constant temperature and has average power. You can replace it with a PTC heating ceramic instead.

At 5V and 180°C, it operates at 4W. Testing shows that at 3.7V, it draws 600mA, which isn't enough power to melt the glue. You could boost the voltage, but given the small battery size, efficiency loss from boosting would hurt battery life. Adding a second battery isn't ideal either, as there's limited space inside, and balanced charging would be required.

So, what's the fix? If one PTC isn't enough, use three.

Testing with three PTCs shows that they can reach 10W, which is sufficient for use. Attach the PTCs with thermal silicone, add an aluminum sheet for heat dissipation, use copper foil for better conductivity, and apply 706 glue on the outer layer for insulation.

Use three power batteries in parallel and install a protection board. A MOSFET should be used to control power delivery to prevent the switch from failing due to excessive current.

If you don't have a heat-resistant sleeve, apply a layer of 706 silicone for some heat protection.

Use two 4056 charging modules in parallel, providing a 2A charge current, and solder a small copper wire for better heat dissipation.

Position the charging port and switch on the left side so you can use a power bank while charging.

Red LED for charging status.

A work indicator light using a straw hat LED, positioned at the front like a power drill, so you can see inside dimly lit spaces.

Testing shows good performance—since the PTC maintains a constant 180°C, there's no glue dripping, and the glue flows smoothly. Modification complete!