In a future version of the thermostat, it would be very useful to have the possibility to power the thermostat via a DC power supply, removing the need to change the batteries.
This is something that has been looked into, but the problem is that tado° is designed to be compatible with a huge range of interfaces, ranging from 20 to 230 volts, some AC, some DC (unlike some of our competitors which are only compatible with 230VAC interfaces), so the problem is that it would require an ultra-wide range input power supply.
An ultra-wide input power supply has a couple of issues, mainly cost and heat-waste which require more complex designs to avoid influencing the thermostat.
It is something we revisit periodically though.
Nest managed to solve this with their smart thermostat, although using the same approach might in the case of Tado only be possible if you have the Tado Extension Kit.
With the Nest the thermostat is wireless - like the Tado can be, and the old no longer used thermstat wires are reused to pass 5v from the Nest Heat Link to the Nest thermostat.
The equivalent Tado scenario would have power passed from the Tado Extension Kit again using the now unused wires to the Tado Thermostat.
(Nest also provide a plugin USB to 5V adapter.)
I would therefore suggest Tado adapt the Thermostat to support running off any 5v power source, this could then be PoE extracted, a USB power adapter, or something else. Lots of IoT products use 5v including the Tado Internet Bridge! 😎
Just remembered that the Tado AC controller comes with a 5v USB power supply. So redesigning the Tado thermostat to support the same power supply would make a lot of sense.
Thanks for the tip. I found one on Amazon, it looks like I would have to in my case cut the supplied cable to put the power adapter at one end and the battery eliminator at the Smart Thermostat end with the existing cable in the middle.
Yes, or just solder a couple of wires to the battery terminals, but bringing the wires out would not be simple and you have to modify the case with some holes.
It would be much simpler if there were a couple of terminals to be connected to a 5 V (or whatever) power supply.
The batteries are for sure the easiest way for someone who just needs to replace an existing thermostat, but for new installations or for someone who is willing to run a couple more cables in the wall it would be great to have this possibility (even without flexibility on voltage, which is granted by the external power supply that you use)