I am working on a hexapod robot that has 18 servo motors(HS-475HB).
My problem is that when I use one servo, the current is about 0.7A at 6V (when moving the servo from its position), when I add more servos the current drops and by the end I get 6 motors running on 0.5A.
The torque that these motors provide is not enough to lift the robot and I could not figure out a way to fix it.
I tried with different power sources for every 3 motors, and the final result was the same, low torque and the robot cannot stand. I also tried with lithium batteries, tested them on 1 ohm resistor and the current was at 2.7A, but for the robot it couldn't go above 0.5A. Another thing was to check the duty cycle, since I was using software PWM from Arduino Mega I thought maybe something was wrong with that and I checked that it was fixed, then I used ESP32 which has hardware PWM on all the pins.
I tried everything I know already but it doesn't solve the problem, can anyone suggest any other ways to fix this issue.