0

Battery power for Nano and 24 Neopixel Ring
Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.

Battery power for Nano and 24 Neopixel Ring

by RandyAtGretchen on Tue Nov 05, 2019 1:49 pm

I am new to using an Arduino Nano powered by a battery pack. I was wondering what would be the best way to power a Nano, along with a single 24 LED Neopixel ring and a Bluetooth module, by using some sort of battery pack. I was initially thinking of using an 8 (AA) battery pack for power. Is that possible or even advisable? What might be a better solution (still using some sort of battery pack)? Lithium Ion Polymer Battery - 3.7v 2500mAh possibly? How long would something like this last, powered up? Assume white lights at 50-70% brightness.

I will have a power switch and it will be off most of the time. The project will be powered up only for short times occasionally. It will also have a Bluetooth module connected to the Nano which will be powered on when the project is powered on.

RandyAtGretchen
 
Posts: 4
Joined: Tue Nov 05, 2019 1:38 pm

Re: Battery power for Nano and 24 Neopixel Ring

by adafruit_support_mike on Fri Nov 08, 2019 2:50 am

An 8xAA battery pack has a nominal voltage of 12V, which would have to be dropped to 5V to avoid killing the microcontroller and NeoPixels. A 4xAA pack is the more usual choice.

You can also use a 5V power brick, and most of our NeoPixels run happily from a 3.7V LiPo.

Of the three options, getting power straight from a LiPo is the most space efficient. Lithium polymer has the highest energy density of the chemistries in the consumer market.

adafruit_support_mike
 
Posts: 59421
Joined: Thu Feb 11, 2010 2:51 pm

Re: Battery power for Nano and 24 Neopixel Ring

by RandyAtGretchen on Fri Nov 08, 2019 4:12 pm

Thanks so much for the info.

I currently have a step down buck converter to drop the voltage from the (8) AA battery pack (12V) to 5V. My only concern then is about how much heat the step down converter will generate in an enclosed box. There won't be anything within 8mm of the converter board and it will be mounted on brass standoffs. Do you think that would work?

I want to run it off a battery pack as opposed to a 5V power brick (so it's portable). I also wondered if the 3.7V LiPo has enough power to power BOTH, the Raspberry Pi and the 24 LED Neopixel ring, with no problems.

RandyAtGretchen
 
Posts: 4
Joined: Tue Nov 05, 2019 1:38 pm

Re: Battery power for Nano and 24 Neopixel Ring

by adafruit_support_mike on Sat Nov 09, 2019 1:40 am

RandyAtGretchen wrote:My only concern then is about how much heat the step down converter will generate in an enclosed box.

As a worst-case estimate, step-down converters tend to be at least 70% efficient (good ones are 95% efficient or better). For every 1W of power that goes to a load, you could expect no more than 300mW of waste heat dissipation.

The easiest way to see whether heat will be an issue is also the best: put the system in a box and see if it gets hot. Foamcore is cheap and easy to work with, and is a pretty good insulator. If you don't have any problems with heat in that kind of test, you can assume there won't be any problems in an enclosure with less insulation.

RandyAtGretchen wrote:I also wondered if the 3.7V LiPo has enough power to power BOTH, the Raspberry Pi and the 24 LED Neopixel ring, with no problems.

A RasPi can't run from a 3.7V power source, so you'd need to replace the step-down converter with a step-up converter like the PowerBoost.

The title and your original post both mentioned an Arduino Nano, which will use much less power than a RasPi.

adafruit_support_mike
 
Posts: 59421
Joined: Thu Feb 11, 2010 2:51 pm

Re: Battery power for Nano and 24 Neopixel Ring

by RandyAtGretchen on Sat Nov 09, 2019 6:25 pm

Sorry, I got confused. Too many projects going on at the same time. Yes, just using the Arduino Nano with the neopixels. No raspberry pi on this project. Sorry for my confusion.

RandyAtGretchen
 
Posts: 4
Joined: Tue Nov 05, 2019 1:38 pm

Re: Battery power for Nano and 24 Neopixel Ring

by RandyAtGretchen on Sat Nov 09, 2019 7:07 pm

Thanks for all of your help with this. I will hook everything up and test it for heat before the final installation.

RandyAtGretchen
 
Posts: 4
Joined: Tue Nov 05, 2019 1:38 pm

Please be positive and constructive with your questions and comments.