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I am pretty new to Arduino and I am making a project with my Uno R4 Wifi, it uses a servo and a motor to push a door closed, and when I power it with a 9v battery it barely moves the door, but when I use 9v wall power, it works very well, maybe better than the USB. But now I'm going to buy a few Nano Everys to make it wirelessly controlled, but the Every doesn't have a barrel jack, so I need to plug + to 5v and - to VIN, I think... but what battery pack should I use that can power the components with enough strength to move the door? I know a traditional 9v is usually horrible, but I was wondering if it's enough for a smaller board like the Nano Every? If not is a pack of 6 1.5 volts better?

I am using a hobby servo (Hi-tec Hs-645 MG), a generic dc motor with gearbox, and a L293D for driving the motor

Thank you!

person595
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Your question isn't really about how to power the Nano Every, but how to power a servo motor. Microprocessors have a much lower current requirement than motors.

Based on this I see that the HS-645MG High Torque, Metal Gear Premium Sport Servo would require 450 mA of current, even with no load, and 2.5 A at "stall" load.

Browsing for the effective internal series resistance of 9V batteries is a little tricky, but I saw one post suggesting it might be around 1 ohm.

Using Ohm's Law, if you are drawing, say, 2 amps trying to close your door, and the internal resistance is 1 ohm, then the voltage drop over that resistor will be 2V, thus there will only be 7V left to power your motor.

I suggest 6 x 1.5V batteries with a higher current capability (say, AA batteries) would be much more suitable than a tiny 9V battery. They really aren't designed to drive motors.

Nick Gammon
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