Does a motor draw power from external battery when Arduino is not connected?

Other Hardware Motors, Mechanics, Power and CNC
1

I have build a robot that uses 2 continuous servo motors for its wheels.
In order to power those servo's I have connected a 9v battery to the servo's. Only the SIG from both servo's is connected to the Arduino. The - from the battery is connected to the GND from Arduino.

I also use a different 9v battery to power the Arduino through its Vin.
That 9v battery is connected using a switch so I can switch the robot on and off when I want.

Now I am wondering, if I disable power to the Arduino, will my servo's draw power from their own battery?
Their is just no signal on the SIG but the + and - are connected to the servo's.
The datasheet from the servo's say they draw 15ma when in static state. Therefore I need to know if I need to disconnect my servo battery as well.

Or will the static state only happen when the Arduino is powered as well?

2

You need to disconnect servo as well. They have their own control logic, the Arduino only provides a control signal.

3

Thanks. That would explain why my battery is dead :slight_smile:

4

This illustrates why the most basic item of equipment that us nerds have should be a test meter capable of measuring volts, amps and ohms. They are available from the likes of Maplins/Tandy for the price of a decent beer (or two).

5

Most servos seem to claim to be good to 6 or 7 volts , so 9 volts may be too much for them.