Powering Neopixel

[codelectron]

Hi,

I have been getting some offers related to neopixel programming. Mostly they are battery operated.
I want to know if Neopixel can be powered with 3.7 V. I know that it is written in the Überguide that it will work slightly dimmer. I want to know if that will work with this battery?.
https://www.sparkfun.com/products/8484 .
WIth will controlled by Arduino pro mini 3.3 V.

Thanks,
Krishna

[adafruit_support_bill]

I have't tried that specific battery, but in general, they do work with 3.7v LiPo cells and 3.3v logic.
(Don't try 3.7v power with 5v logic. That will kill the pixels).

[codelectron]

I have't tried that specific battery, but in general, they do work with 3.7v LiPo cells and 3.3v logic.
(Don't try 3.7v power with 5v logic. That will kill the pixels).

Thank you
Krishna

[michaelmeissner]

It depends on the neopixel, many of the earlier ones that the various wearable tutorials were written about could be run at 3.7v on a 3.3v processor. However, it appears many of the newer ones now need closer to 5v power that the spec requires. Some of these will work with 3.3v signaling, but some so-called grumpy strips also need 5v signalling.

I have a 24 LED ring from Adafruit that will not work when powered with a 3.7v Adafruit 1200 maH lipo battery and my Gemma. It will work if I hook it up to 5v and use a 3.3v Gemma/Teensy to drive.

So far, all of the neopixels I have bought and used, will work when powered with 5v, and used with signalling with a 3.3v processor. However, some people have found various WS2812B lights that also need 5v signalling. Here is a post where somebody looked at various voltage signal converters, and came to the conclusion that for small amounts of neopixels, the TXS-0102 would work, but for a lot of pixels, you need a 74HCT245 chip (which Adafruit is now selling): http://happyinmotion.com/?p=1247

That still leaves the problem of voltage. If you don't want to deal with voltage converters from 3.7v and you only are running a few neopixels, you might want to look at portable chargers meant to charge cell phones, such as the Minty Boost that Adafruit sells: https://www.adafruit.com/products/14

Another alternative is to get a battery pack that takes 6 AA rechargeable batteries (7.2v nominal voltage), such as: https://www.adafruit.com/products/248, and a step-down converter to 5v/1a: https://www.adafruit.com/products/1065. If you need even higher amps, I've seen this in the store: https://www.adafruit.com/products/1385. You can use smaller number of batteries and use a step-up converter instead, but there you likely won't get the amps needed for a healthy amount of neopixels.

I recently picked up from ebay a power charger that uses two 18650 batteries and has 3 USB outputs (5v) plus a selectable power output (5v/2.1a, 9v/1a, 12v/0.6a) that is slightly bigger than an Altoids tin, and I got it because it can deliver 5v and 2.1a for neopixels, or 9v/12v for some other things requiring higher voltage. I haven't done a full test yet, so I can't tell you how long it would last in the field.

Now for a big neopixel setup, you need to properly design the power setup, with distributed power, and appropriate sized power buses. That is way out of my league, but the Teensy 3.1 with the OctoWS2811 adapter, or the Fadecandy seem to be the platforms of choice in those setups.