I have no idea about the limit of sensors that can be used on a particular firmware. There are several other options, do a quick google search. If the firmware, and not the wemos, is the limiting factor then you may need to write your own code to handle all 20 sensors. This is something you will need to search google and find a solution for.
Check the wiki for Esp Easy if I remember correctly you can have the wemos publish the wifi strength, not sure about the firmware version.
Honestly, with that many sensors, I would use multiple microcontrollers. In the short term, you might save money by buying less controllers, but if the one single controller fails, you lose all measurement possibilites at once.
If you already have all the wires going to one central place, then mount two (better three) D1s there, and give each of them 7 sensors. That way, you even get some fail safety.
Thank you Hakan.
I allready read that post but is not very clear if is working and in wich way he did it.
My projet is to power 2 Wemos d1 that have 7/8 ds18b20 and dht22 sensors connected with only 1 power supply.
If it is possible wich one is the best way to do it?
If you want to have a very simple setup, just take the cheapest possible powered USB hub, and use micro-usb cables from the hub to the Wemoses to power them.
A slightly more hacky way would be to take a power supply, cut the USB cable, and wire the +5 and GND lines from the power supply to the VIN and GND pins of the Wemoses. If you want, you could solder this on a little piece of perfboard so you don’t have dangling cables all over the place, and it would look tidier too