Hello again all! While not strictly about LEDs,

(Marty Fox) #1

Hello again all! While not strictly about LEDs, I purchased these Anker external batteries for my Burning Man jacket project utilizing FastLED code, but it shuts down whenever connect the lights. However, I don’t think it’s because of low current at the start but because it detects a short. When use a multimeter on the + and - terminals of my lights there’s definitely a closed circuit, but not as strong as if I connect my leads together. I’m using 200 WS2812B’s with capacitors and power at every 40th LED and a resistor at the start. It works fine when I use regular batteries but I don’t think six AA’s (a pair of three AA’s in parallel) will last long.

Does anyone in our awesome community have a recommendation for portable power that’s not to smart for its own good?


(Daniel Garcia) #2

If you’ve got a short you should really fix it, not look for a power supply that will happily keep shoving power at you.

(Marty Fox) #3

I hear you, but there seems to be some power getting through naturally on a short segment of 13 lights I just disconnected from the main array. For what it’s worth the circuit is practically closed on a segment of 13 lights with a capacitor across + and - (1 ohm). On a segment of 13 without a cap it’s around 50 ohms.

(Robert Atkins) #4

@Marty_Fox , you’re not connecting both positive outputs of the Anker’s USB ports together in parallel are you? They really don’t like that—Ask Me How I Know™.

(You should tie the grounds together though.)

(Robert Atkins) #5

Also, jacket project? Pix pls! :slight_smile:

(Luminous Elements) #6

Do you have a choke (a.k.a. ferrite bead) in between the power supply and the capacitor to limit the inrush current? The small amount of inductance added by a choke can prevent power supplies from detecting a “short” when charging a capacitor.

(Marty Fox) #7

Actually,@Robert_Atkins , I’m borrowing a bit of your code, but I was going to thank you when it was looking like it was going to be a success, which it is. So thank you thank you thank you (I stand on the shoulders of giants - in fact, I have one question for you which I will ask in another thread). I initially had one 1000uF,6.3V capacitor at each of the five power points, which I had learned from Adafruit was necessary to limit the rush of current, but I removed all but the first one and it’s working great now (so thank you as well, +Luminous Elements. I am only using one external battery, but as a backup I intend on using six AAs (two groups of three in parallel). Pictures forthcoming. Thanks!

(Luminous Elements) #8

@Marty_Fox , best practice is to de-rate the capacitor a little, and use a cap that has at least double the normal voltage of your circuit. This helps when the device is powered up while extremely hot, cold, etc.

(Marty Fox) #9

@Luminous_Elements , do you have something specific in mind? Also, please note that I’m learning everything as I’m going along. :slight_smile: Do you think I’m endangering the lights by just using one 6.3v cap? Thanks!

(Marty Fox) #10

By the way @Robert_Atkins I’m using these lights. http://www.aliexpress.com/item/40mm-spacing-IP68-WS2812B-LED-pixel-string-addressable-rgb-full-color-DC5V-input-40pcs-a-string/32261145173.html
I have high hopes for their durability. Also, this will be a vest, although my wife made the arms re-attachable, which might also double as leg warmers. Also, the really helpful part of this project is use of bird netting to secure the lights between the fur and lining. I’ll describe more in detail later. Thanks!

(Luminous Elements) #11

@Marty_Fox , I don’t think it’s too big a problem so long as you’re using an electrolytic capacitor – it probably won’t be nice to the skin or nostrils if it goes, but so long as it’s not tantalum it won’t take out your fingers or the eyes of bystanders. I have also heard that overvolted caps fail shorted, but this entire comment is of course hearsay and you should probably not trust it as legal advice.

(Randal B) #12

I use those types of packs almost exclusively for my portable wearables without issues (150-200 leds). I only had one type auto-shutoff after a time, but easy enough to turn back on.