Quite often I am faced with soldering jobs that require portable irons.

The HS01 from Fnirsi seemed to fit the bill of my requirements and so I ordered one and after several months of ownership it has proved to be a very useful tool and I wanted to write a small review of it so here goes.

The unit is also sold in other markets as the Kaiweets KETS02, the only difference is the kaiweets unit is supplied with a heavy duty rubberised usb c cable.

I found the Fnirsi HS02 for the bargain price of under £45 GBP/$58 USD complete with 6 tips from Kunkune here in the UK


The unit arrived next day


The six tips are very useful sizes for general soldering and very small work. I was very happy with the quality of the unit, all aluminium casing and included is a cover made of the same material so that the tip can be totally covered when you power the iron down. There is a usb c to 2.1mm/5.5mm jack for providing power to the unit from a source of your choice. I use a Dell usb c power supply Model Number : HA65NM190.

I have also used an old Lenovo Laptop 20v/65w PSU by just changing the DC plug and using that with the supplied USB-C pigtail lead.

Also I tried 12v by making up a cigar lighter lead and same pigtail.

The instruction guide gives you the available voltage feed options, 9v,12v,15v and 20v.


On first test the iron was set to 20v and it heated up to 350 degrees in no time at all.


For the first time of use I noted the unit would fluctuate between 310 and the selected 350 degrees.

This I thought was a fault with either the iron or the PSU  but the fault turned out to be with the user !

TIP : New owners, You must remove the collet each time you change a soldering tip.  Do not try to change tips without removing the collar as the above fault symptoms will be the result.

Note how the ridge in the tip is seated firmly against the iron right up until it stops, then replace the collar.


I have completed many jobs with the Fnirsi HS01, it has been one of the best tools I have purchased.

So versatile !



Firmware Update

Recently I found a new firmware file on Fnirsi website and software to change the firmware.

The Fnirsi firmware tool is poor and in Chinese language so I decided to look at Kaiweets website where they have the same software but in English language.

I flashed the firmware using

Kaiweets KETS02 firmware flash tool.






Fnirsi Firmware file (S19 file type)  as the date of release was more recent than the Kaiweets one (link below)






Tip : Before you start, pick a good quality USB-C cable, using poor cables will result in the device not being recognised by the firmware update tool.

The Fnirsi HS01 is recognised in the program as a Kaiweets KETS02 iron as they are exactly the same internally.


Here is a quick video of the firmware change of my unit.



Overall verdict.

The Fnirsi HS-01 iron is a superb device, it can hold its own to a standard size station and it will come in particularly useful for very small PCB work or for portable for use in automotive applications.

The vendor (Kunkune)  I have no hesitation in giving a 5 star recommendation.

Kunkune UK have keen pricing strategy and the costings are very close to those of Aliexpress and next day delivery for UK buyers and fast & economical delivery options for Europe and worldwide.

Often cheaper than Aliexpress when you factor in the tax and delivery charge.

What is not to like ?

Check out Kunkune trustpilot rating