Wearable Power source - namely USB Chargers (and other 5v power).

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(Randal B) #1

Wearable Power source - namely USB Chargers (and other 5v power).

In previous wearables I’ve simply used some smaller usb chargers to provide the 5v to the arduino, and used that same power to power up to 150 leds.

I’m looking to run a teensy with 600 leds and I purchased a few larger USB chargers to try out.

I’d like to have two to power 1/2 of the LEDs (two circuits).

Questions:
1- I’m having issues by passing the “smart” power of a couple of them. so if I power my teensy separately , the USB wont power my LEDs. Suggestions?

2- My plan is to have power input at LED 0 and LED 299, with another circuit power at LED 300 and LED 599. using two different power sources, with only the data line connected between them. Should I add additional power inputs along the way? (+Robert Atkins I know you made a powerbus and powered each strip individually. )

Debating buying more smaller USB chargers and swap them more often rather than fighting these large ones, but the larger ones have 2.0A outputs I need.

(Marc Miller) #2

You’ll probably need to inject power about every 100 pixels.
You MUST have a common ground connection between everything.
Do NOT connect the positives of the two batteries.
Example wiring:

If you power the Teensy externally, you should cut that little trace on the bottom so it doesn’t get power from USB any more, cut the +5V wire in a USB cable, or use one of the other suggestions for when powering externally.
https://www.pjrc.com/teensy/external_power.html
https://forum.pjrc.com/threads/19228-confused-again-Cutting-VIN-from-VUSB-Teensy-3-0

(Leon Yuhanov) #3

My last Wow Suit has 2300 LEDs i ran it using 6 x 10ah 5v power banks all connected in parallel. +Marc Miller why do you say not to connect the battery + together? I have all 6 connected to a small power distrubution board and have never had issues

(Marc Miller) #4

If all the batteries are the same type/size you’ll probably be fine until one battery starts to go bad and then the load won’t be balanced any more. The others will try to equalize the potential across all batteries leading to premature battery failure, which then makes things even more unbalanced, which leads to further attempts of balancing, leading to more battery failure and kaput. Unless you have the right sort of circuitry to prevent that it’s usually not recommended.

(Randal B) #5

@Leon_Yuhanov connecting the powers of these usb charger packs will fry them (even connecting two outputs from the same one will fry it). Ive always used the usb charger ones for ease of use, but i need to use one that has at least two 2A outputs (4A total if possible.)

Can you link your batteries you used? exploring everything right now

(Chris Creel) #6

This one can drive a ton of LEDs. It’s heavy, but I ran a nighttime half marathon wearing it, so it’s definitely wearable. http://amzn.com/B012NIQG5E

(Randal B) #7

@Chris_Creel I have one exactly like that to try out. How did you wire the power from it? previously i used the usb connector on the teensy and powered small number of leds off of the teensy. I tried making a power only usb to +/- wires to a breakout board, but the powerpack doesnt want to power the busbar. (but works if i plug into the teensy directly).

(Leon Yuhanov) #8

@Randal_B Not sure where you heard that. I have a whole bunch of different power banks that i have used many many times over in the same parallel config with 0 problems. No overheating no issues at all!

(Leon Yuhanov) #9

Also check these out http://www.ebay.com.au/itm/151484787065 ive been testing one of these on a project recently. I have 4 of these http://www.ebay.com.au/itm/182130693248 which i have opened up and soldered a cable directly to the battery terminals on the inside(each bank has 5 x 18650 in parallel). 2 x 2 banks in series connect to the input of the SBEC and I get 5V at about 6A at the moment i havent pushed it further yet.

(Leon Yuhanov) #10

I have posted a small write up on my blog https://plus.google.com/102639486677013343669/posts/iiKgG9xe5B4 if anyone is interested

(Randal B) #11

@Leon_Yuhanov I see now what you mean now! I think Robert (and i) were leveraging the USB port to send power, we werent tapping directly to the power like you were. thats brilliant.

(Leon Yuhanov) #12

@Randal_B Most of those cheap power banks are supposed to push out 2A on 1 port and 1A on the second. But they rarely work properly. So i found it easier to just go directly from the cells. This way you have a safe battery module with its own charger!

(Marc Miller) #13

If you’re drawing power directly from the cells are you bypassing the battery’s safety system?

(Leon Yuhanov) #14

@marmil In the case of using the SBEC yes I am! I am well aware of the issues this can cause :slight_smile:

(Marc Miller) #15

@Leon_Yuhanov I would caution against calling this a “safe battery module” without mentioning this could have potential issues. I do love that you’re pushing the envelope and discovering new possibilities, but please do be clear when it comes to safety issues. You make awesome stuff and new people (which might not yet be aware of those issues) will be inspired to follow your lead. Help them be successful too. :slight_smile:
“With great power comes great responsibility.”

(Leon Yuhanov) #16

@marmil Agree with you completely. I should have mentioned that this MAY NOT BE A SAFE THING TO DO, because you bypass the battery protection