BoB the Biped.

So I got the Bob body 3d printed got my 4 servos and a HC-SR04 sensor all hooked up to a Arduino nano. The problem I am looking for help on is, When hooked up to a 3.7 v Lipo batter (from a cheap quadcopter) it does not utilize the sensor, when it is hooked up via the usb cable it works just fine. I know the voltage of the battery is lower than 5 volts but it the only one I have that fits. I use the 5v pin for the servos and sensor (all in series) and the vin and ground next to it for the battery. The other ground next to D2 is used for the servos and sensor ( again in series) I do not have schematic drawn up. If anyone knows of a good schematic drawing program that would be great. Thank you in advance.

The battery you have isn't going to power those servos. You really need around an 800mA power source at 5V at least to power the controller, servos, and the sensor.

That is what I thought but I wanted to reach out to know for sure. But I hook 2 up in parallel to increase voltage and it doesn’t do any thing. voltage around 8 volts.

Servos typically need between 4.8 vdc and 6.0 vdc - 8 volts has a high chance of damaging the servos.