Powering Arduino

Other Hardware Motors, Mechanics, Power and CNC
1

I have a Tenergy 2600 mAh power pack and I'm trying to run the Blink program on an Arduino Nano clone from LCSoft. I think it has an FTDI 232 chip for the USB side.

Arduino will reset after about 20 seconds. I wonder if the Tenergy power pack is pulsing the output or if something else is interacting? This Arduino board runs fine when connected to the PC USB.

I am using the same Nano board to run two Futaba S3003 servos and a simple program to exercise the servos. I've set up a 5V supply node with four AA rechargeable batteries and plugged the servos and the Nano Vin pin into that node. Nano is unstable with that supply alone, but will be fine if connected as well to the PC USB. Nano will reset periodically if I use instead the Tenergy power pack and four AA batteries.

What I'm confused about is that I read that the Vin pin generally requires a little over 6V minimum for the regulator, but I see a lot of examples of folks using four AA batteries (i.e., http://www.instructables.com/id/Power-your-Arduino-Uno-with-four-rechargeable-AA-b/)

Has anyone else had issues with an external USB power pack? And is there a pin on the Nano that supplies directly from the USB port input so I can get power to the servos without burning out the regulator?

Otherwise, I think I will need to use six AA batteries for this project, or get a step up voltage regulator, or can I plug the 4 AA pack into the 5V pin?

2

The Vin needs around 7 or more volts.

Do not plug the 4 AA battery into the 5v input unless you want to buy another Arduino.

Weedpharma

3

Hi,
If you read

You will notice RECHARGEABLE, four of them gives 5V, four primary batteries gives 6V.

So note RECHARGEABLE, just don't recharge them with the arduino connected and turned ON.

Tom... :slight_smile:

4

I still have not found an easy way to power my Nano and two servos.

I tried using a voltage selectable 800 mA wallwart and set 6V and 7.2V. I monitor the Vin voltage fluctuates about 1/2 volt when the servos move. I tried placing a 10 and then a 47 uF cap on the supply and that did not help. Arduino keeps reseting when the servos both move, I guess because of the voltage fluctuations? And the system goes unstable and starts to act weird, like running slow and making an off pitch.

The walwart voltage is a bit higher than set and was showing as much as 8.5V when set to 7.2V. I don't want to fry the servos either. They are supposed to run at up to 6V.

So, what would be the recommended way to power a Nano and two standard Servos? It looks like I need two independent supplies or build a step-up voltage regulator just to power the Nano?

The system works fine if I power the Nano from the PC USB and power the servos with the 4AA batteries, when I tie the grounds together.

5

The system works fine if I power the Nano from the PC USB and power the servos with the 4AA batteries, when I tie the grounds together.

So replace the PC USB with a 3 AA battery pack connected to 5V pin, and 4 AA for the servos. Keep the grounds tied together.

6

Thanks. I was trying to build this easy servo robot and ran into this issue with power.

Mine is a little bigger so a 9v is not going to be enough to power it for very long, so I thought I could get away with 4AA directly with some caps.

I still don't understand why supplying power to the 5v pin wouldn't burn out the on-board regulator. Looks like that it connects direct to the output pin of the regulator (U3). I'm surprised also that regulator chip is overloading with the two servos just freewheeling when supplied with a wallwart, it's supposed to be able to output 500 mA. And then the issue with running the Tenergy pack and a simple blink program, so I wasn't sure if something else wasn't amiss with the Nano, or I'm just missing something...