Powering Mass Number of LED Strips - Teensy 3.1 & WS2812B LEDs

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d1ode

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I am planning on using a Teensy 3.1 to drive up to 500 RGB LEDs, specifically the WS2812B LED Strips. Unfortunately, these things suck up 60mA each which comes to 30amps if 500 of them are on full white.

Well, I need to power these things for 2-3 hours with a battery that I can easily fit in my pocket. Let's assume the average current is 25mA each or 12.5A total. The strips are run off of 5V.
I am planning on putting these strips on my clothes, so safety and size are important for the project. I also want to keep costs low, maybe by sourcing from mouser, because I might replicate this.

I've been thinking about using a large capacity 11.1V LiPo battery and then a dc-dc 5V switching regulator to power everything. Maybe having like 10 of the 3A switching regulators soldered right into different segments on the strips. This way I can run smaller gauge wires to the strips since it'll be lower current until it gets to the regulator??

Any thoughts on the following?
  1. kind of battery (LiPo, Lithium, ?)
  2. voltage for the battery? (higher voltage or lower voltage)
  3. should I use a dc-dc switching regulator? One large one that can handle the full 30 amps or a like ten of the 3A ones?

Thank you in advance!
 
The strips ar 5V so any more battery voltage will just cause more work for the DC-DC coverters resulting in more heat having to be dissipated.
 
Alright, but I'm having trouble finding a 5V (or close to 5V) battery that has enough capacity to run these for a significant period of time. It seems LiPos also are only available in 3.7V, 7.4V, or 11.1V. The lower voltage ones don't tend to have very high capacities (like 5000mAh and lower).
 
Are you going to be on stage or are people going to be near you? I've had complaints that running 32 neopixels at a power level of 30 (combined for red, blue, green, which is roughly 75m total) can be hard for somebody talking to me face to face. I can just imagine what 500 LEDs at a much higher power level would be like. If you've never used ws2812's, get some and figure out what is an appropriate power level to use would be.

If you are trying to keep the costs low, perhaps you should see if you could do with fewer LEDs.

With the 144 LEDs/meter strip that Adafruit sells, you are talking about 4 meters of LEDs, and 16-17 meters of LEDs if you go for the 30 LEDs/meter strip.

Consider getting several batteries to power segments of strips, rather than trying to get one battery that does all of the strips. Adafruit does sell this 5v battery (10A capacity, 2A power): https://www.adafruit.com/products/1566
 
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I had the same problem finding suitable batteries, the best I could find were 7.4v li-on batteries. For that project we were using small sections that each had a 7805 which is far from ideal.
Do a search for sbec/ubec, they are very small dc-dc converters used in model airplanes and are quite efficient. Otherwise polulu has some nice converters too.
 
This sounds kinda dangerous? 500 leds at full brightness would be pulling some serious amps, make sure you have your power supply water proofed and I hope you are using the water proof leds since my leds have power, signal and ground pads exposed every led which would make it very easy to short if any moisture got on it.
 
Are you going to be on stage or are people going to be near you? I've had complaints that running 32 neopixels at a power level of 30 (combined for red, blue, green, which is roughly 75m total) can be hard for somebody talking to me face to face.
People will be near me, I won't be on stage. I can always dim the LED's via code if that's a problem. I will also play around with fabrics on top of the LEDs to diffuse the light.

Consider getting several batteries to power segments of strips, rather than trying to get one battery that does all of the strips. Adafruit does sell this 5v battery (10A capacity, 2A power): https://www.adafruit.com/products/1566
That's an interesting idea and a pretty nice looking battery. I wonder if I can find that battery for cheap on alibaba.com.

I had the same problem finding suitable batteries, the best I could find were 7.4v li-on batteries. For that project we were using small sections that each had a 7805 which is far from ideal.
Do a search for sbec/ubec, they are very small dc-dc converters used in model airplanes and are quite efficient. Otherwise polulu has some nice converters too.
Oh good, it's not just me having this problem. I did come across the UBEC's in my research. Such as this one from Adafruit: https://www.adafruit.com/product/1385 I can't figure out what the extra hardware in that is for though, such as the capacitor. I was trying to locate something similar to that on mouser/digikey that I could use, but could only find the underlying barebones chip, the MP2307.

This sounds kinda dangerous? 500 leds at full brightness would be pulling some serious amps, make sure you have your power supply water proofed and I hope you are using the water proof leds since my leds have power, signal and ground pads exposed every led which would make it very easy to short if any moisture got on it.
Is that dangerous?? Crap... Well, the good news is I will be making sure everything is water proofed. I'll have the LED strips incapsulated in plastic tubing and I'll stick in some in-line fuses. Hopefully that will make it safe.
 
I'm trying to keep the number of LEDs at 500 as I want the pixel density. I can have the code dim the lights so that they draw less power and in turn make the battery last longer, but I want to make sure I design for the worst case scenario; all LEDs on full-white. I wouldn't want the thing to explode when I do that. So, as long as the final design is able to handle the max current, we should be good.
 
If you haven't seen it before, you might want to check out the octows2811 adapter that PJRC.com sells that updates 8 parallel streams of LEDS, and it also has tips about wiring: http://www.pjrc.com/store/octo28_adaptor.html.

Also be sure to read the Adafruit uberguide to neopixels, which contains various best practices: https://learn.adafruit.com/adafruit-neopixel-uberguide/overview.
Thank you for the links. I actually have read those and I do have the octows2811 adapter. Unfortunately, neither of those sites really help too much with my battery supply problem.
 
Thank you for the links. I actually have read those and I do have the octows2811 adapter. Unfortunately, neither of those sites really help too much with my battery supply problem.

we found the our estimates of power use were over what we actually use. We made up our own power packs, you might want to consider it. I soldered rechargeables in two packs of four, each pack giving 4.8v, but in parallel we managed to bump up the Ah. So, each part of the pack was 4x AA at 2400mAh, and this was doubled by using in parallel. We found that this pack ran 60 ws2812 leds for five hours on a pattern that was a constant rotation through the spectrum. not quite what you need, but the idea is that you might be able to put your own together.
 
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we found the our estimates of power use were over what we actually use. We made up our own power packs, you might want to consider it. I soldered rechargeables in two packs of four, each pack giving 4.8v, but in parallel we managed to bump up the Ah. So, each part of the pack was 4x AA at 2400mAh, and this was doubled by using in parallel. We found that this pack ran 60 ws2812 leds for five hours on a pattern that was a constant rotation through the spectrum. not quite what you need, but the idea is that you might be able to put your own together.
That's very interesting. What AA rechargeables did you use? Were they Ni-MH?
 
yes, Ni-MH. perhaps a bit old school, as in, increased the weight and bulkiness, but I had to come up with something that the users were willing to afford. The system uses a standard charger (from a radio controller setup) via a power jack in the project box, so no issues with changing out batteries but the user. A rotary three position switch means that the circuits for charging and powering the teensy and leds are separate, so teensy and leds are only ever powered from the battery pack and can't receive v from the charging circuit. the three positions are: charging/off/teensy+leds on.
 
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