Powering a 101 with 5.5V

Hello everyone,,

I have a regulated 5.5V power supply but when I attach the power line to Vin and ground to GND the Arduino does not turn on. I suspect this is because Arduino 101 wants 7V minimum on Vin. I am wondering what the best approach for powering this Arduino is.

Note: I will have inputs up to 5V, not sure if this makes a difference.
Other note: I will also have access to an 11.1V 3S battery in the system, however it will be have high currents on the leads so I would like to avoid hooking anything up to it for the Arduino

Some approaches I have considered:

1.) Attaching the 5.5V power line to the 5V output, I read that as long as it is regulated a 5V input on the 5V pin will sufficiently power the Arduino. I have briefly attempted this and the Arduino did turn on. However, I have .5V over the 5V limit and am unsure if that can cause damage.

2.) Attach 5.5V line to 5V output through a resistor to lower the voltage to 5V. I am unsure of the currents the line will see and so do not know which size resistor to pick to drop .5V, or if this is necessary.

3.) Attach the 5.5V line to the USB input. I have space imitations so this is not ideal, nor am I sure how well this would work.

4.) Step up the 5.5V line to >7V and attach the line to Vin. I would like to avoid building more circuits as I am already low on space.

5.) Tap into 11.1V battery for power. Not sure if safe due to high currents, don't want to build more connectors.

I think that's everything I have thought of. Any advice on what the best way to do this would be helpful. I would like to go with approach 1 or 2 if I can determine that its safe. My main priority is simplicity and lack of needing additional connectors/circuitry.

Thanks a lot!

How about connecting the 5.5V supply to the 5V pin via a silicon diode which will reduce the voltage to approx 4.8V? That's what I'd probably do.


If your regulated power supply is adjustable,
perhaps you can dial it down to 5.0 v out.

The Vin pin serves the same purpose as the barrel jack. The only difference is (usually) that it doesn't go through the schottky protection diode that causes a small voltage drop. Take a look at the minimum input voltage requirement for the voltage regulator, It will require at least 6.5 Volts maybe a little more to make it work. If you make the connection you will be under powering the Arduino and no promises of what it will do. It possibly will run perfectly or it could drive you craze with weird problems.

The official statement is as follows:
The board can operate on an external supply from 6 to 20 volts (That is VIN). If supplied with less than 7V, however, the 5V pin may supply less than five volts and the board may become unstable. If using more than 12V, the voltage regulator may overheat and damage the board. The recommended range is 7 to 12 volts.

Good Luck, and Have Fun! Gil