With larger blades, why does the drone have less thrust

I recently upgraded my six-rotor UAV.In order to improve flight efficiency, I specially refitted larger blades. But when it was installed, I tested it and found a series of problems. Firstly, the electric power is very hot, and secondly, it is obvious that the thrust of propeller is getting smaller and smaller. Can someone tell me why?

A larger prop will work the motor harder, draw more amps creating more heat.
Post a log and photo for better answers.

Hi!
First of all, you cant randomly change your props without check the motor specs. You need to understand the motos has 3 important specs:
-Voltage or ā€œSā€ of operation
-KV, that tell you in a big point of view how fast the motor spin
-the PROPS you can use.

In general, high KV use small props, for example a 900KV use 10" props. On the other hand, an agriculture drone has 100KV motors (very big ones), and use 33" props.

A 900KV motor trying to move the 33" (imposible, but as an example) porps will produce an excesive use of current and of course, heat, the motor will melt inside trying to move that prop.

So, if you want to use bigr props, first look for the motor spec chart, like this one

In red you can see the Max amps the motor will use with a 6S battery, with a 12" prop, and the weight you will lift. thats is the numers you need to know

In the other hand, if you are going to fly over 5000 sea level, you can use biger props or a 3 blade props to compensate the missing air, but you have to caclulate what do you have to use.

Bye!