- jremington thinks the power supply won't be enough. I have no idea how large 20kg servo is but he is experienced and probably right.
- You CANNOT use voltage divider for such thing, there are special circuits for this. It is quite complicated and likely out of your reach to design and make such circuit yourself. You need either a lot of experimenting and reading or buy suitable power supply. Anyway you need to know voltage and power rating of the servos.