Hi, I built a quadruped robot consisting of 12 servos. 4x servo type medium (Power HD HD-1160A with plastic gears) and 8x servo type micro (MG-90S with metal gears), servos are powered by battery pack (4x AA battery 1. 5V) 6V and Arduino mega, which power 5V. After two steps, the robot collapses and the medium servos switch off (servos placed on the frame of the robot) and the micro servos operate and perform further leg movements. I suspect the problem lies with the power supply of the robot, the battery pack adds weight to the robot and may not be a very optimal power source. After connecting the voltmeter, the meter showed ~5V instead of the required 6V. The second problem may be the medium servos I use, at 6V the torque of the servo is 2. 7 kgcm and the micro servo legs have 2. 2 kgcm also at 6V. After removing the battery pack, the robot worked fine until a certain moment when it collapsed, the servos stopped being "tensioned" which would result from the lack of adequate power. Do any of you know where the cause of the problem may lie? Thank you in advance.
Hello.
Servo motors consume current even when they are not moving and only need to stay in a certain position. Do you seriously expect to power 12 servo motors normally with just these batteries? You need about 1.3 amperes just to move these motors and that at idle, and at maximum load the consumption is almost 6.5 amperes. You can't do it with those little batteries.
MG90S x8
Input Voltage: 4.8V - 6.0V.
Operating Current (5.0V): ~2.7mA (idle), ~70mA (no load), ~400mA (Stall)
Rotation Angle: 0° - 180° (Resolution: 1°) Max Speed (5.0V): 0.6 deg/ms (full 180 degrees in 300 ms)
HD-1160A x4
Current consumption in idle state: 5 mA.
Current consumption with no load: 180ma.
Current consumption maximum: 800 mA.
Hello, so what alternative power supply option do you recommend?
(8 * .4A) + (4 * .8A) = 3.2A + 3.2A = 6.4A (max) @ 6VDC
I have no experience with robots, but maybe 4 accumulator cells of 18650 batteries connected in series and 2 mini560 DC to DC buck converters, each one feeding a separate type of servo motors.
Hi, @kliwmojt
Sorry had to spread it out to point form.
Can you please post a copy of your circuit, a picture of a hand drawn circuit in jpg, png?
Hand drawn and photographed is perfectly acceptable.
Please include ALL hardware, power supplies, component names and pin labels.
Thanks.. Tom.. 
Thanks!!! Do you think that one 7,4V lipo battery that i got from my airsoft replica(https://militaria.pl/p/akumulator-asg-specna-arms-li-po-7-4v-1200mah-15-30c-dwudzielny-t-connect-39341) and a step down converter(XL4015 1,3V-36V 5A) would work? I would change the output voltage to 6V and set i for like 3-4 amps? Or should I buy a seperet battery?
The XL4015 may have a maximum current of 5 amps, but realistically, I don't think it's a good idea to draw more than 4 amps from it. If you use 2 XL4015's there should be no problems. The batteries you mentioned have a capacity of 1200mAh, which means that with a maximum consumption of almost 6.5 amps on all servos, the robot will work for about ten minutes. Also, you will only have a 7.4 - 6 = 1.4 volt difference, which I think may not be enough for normal operation of the XL4015 at such a high current.
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