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View Full Version : Teensy, Ws2811 and 18650 litihium ion batteries



markvr
10-15-2013, 12:29 PM
I don't have a Teensy yet, but am investigating the feasibility of building a battery powered display using OctoWs2811 and up to 10m of 5v ws2811 ribbon. This combo looks like it has awesome potential, especially once I found out there are FFT routines in the core of teensy!

I already have a load of 18650 LiOn batteries I'd like to use, which are 3.7-4.2V. Does anyone know if it's possible to power the ws2811 ribbon with 3.7v direct from the batteries? It will obviously not be as bright, but I wonder if it would work at all?

Failing that, I guess I would need to wire two batteries in series to get ~8V, and use something like this - http://www.ebay.co.uk/itm/Turnigy-Dlux-10A-Regulator-Switch-w-Dual-Battery-Redundancy-UK-STOCKED-/231065711775?pt=UK_ToysGames_RadioControlled_JN&hash=item35cc96f49f , or this - http://www.pololu.com/catalog/product/2111 - but it would be easier and more efficient to not require the regulator.

thanks, mark :)

cartere
10-15-2013, 02:20 PM
I have been doing this for a set of lights on my recumbent trike, works well with 3.7 volt battery pack. Be aware that long strips draw a lot of current, that LiOn batteries can be dangerous, would recommend the use of protected cells or have a battery protection circuit board. Last night was in a hurry and hooked up my strips to the 3s (11v) battery instead of the buck converter, instantly fried 144 leds. Will change connectors so that will not be possible in the future :) The issue I have with 1s(3.7v) batteries is that you only get about 1/3 capacity before every thing shuts down due to to low voltage, worked adequately with about two hour run time (6600 maH) battery with various animations on a 144 led strip ( now defunct, replaced with 60 led). 60 leds should give much better run time and not have to use buck converter and 3s battery.

markvr
10-15-2013, 03:09 PM
Hi thanks for the info. What voltage would you say the strip stops working at? The batteries I am using are go from 4.2 to 3.7V, so if the strips stops working at 3.7 that is fine, but if it stops below 4V it won't use all the battery capacity.

I will have up to 600 LEDs so need some serious battery power. Prob going to use 12 18650s. It would be good to avoid needing to use regulators as I'll lose some efficiency that way. Maybe I will need to though :(

Also, has anyone used the 12v WS2811 ribbon? This would be much easier because it will need less current in the wires and no regulator.

PaulStoffregen
10-15-2013, 07:46 PM
The WS2811 strips I used had trouble under about 4.4 volts. But when they were on 100% white, the voltage at the end of a 1M strip was 0.25 volts less than the input. The new 2812B's are probably better. Still, at these high currents, the resistance of your wires and the metal in the flexible strip does add up and cause some voltage loss which depends on the total current used, so don't neglect that issue.

markvr
10-15-2013, 09:45 PM
Cool thanks Paul! I'll probably not have any strips > 1m, but I was considering running power and gnd to each end anyway to avoid any probs caused by the voltage drop down them.

Sounds like the most reliable option will be to us a 6x2S batt setup, and a switching regulator. Oh just for info it turns out the 12V strip is essentially wired up with 3 LEDs in series each time, so only cuttable every 3 LEDs, and for what I'm doing I need it to be cuttable more accurately than that.

BTW - I've been using Arduinos for a bit and have just discovered Teensys. I don't have one yet - just trying to scope out what I need for what I'm trying to do - but they look a lot more advanced and somewhat cheaper than Arduinos Due, and I'm hugely impressed with the amount of work you've put into all the libraries as well!

FinOminal
03-13-2014, 10:28 AM
I ran 40 WS2801 chips, and also have run WS2812b chips off one 3.7v 18650.

Worked fine for me and ran down to about 3 volts.

I got a full night on the playa at burning man on a conservative pattern (running the lights max 64 brightness)

The controller tends to go to sleep before the lights do.