Hi, guys i need some help yet again. So last time you helped me figure out that i wasn’t providing enough power to my strips. I tested and confirmed that theory. My questions is: How many amps can i get from 8 AA batteries? That would produce 12v (which i need for the circle WS2812 LED (12 LED total)) and then i plan on using a 12v to 5v converter (pictured) to power the 5v ws2812 LED strips. (My arduino nano runs off 5v BTW) Would this work? I need about 3 amps from the 5v and barely any from the 12v. I need to use batteries for this project so if that doesn’t work, can someone propose a better 12v/5v solution?
That converter that you have pictured is marked as 3.7v - have you checked the output of it to make sure you’re getting 5v?
Also, how many leds are you running that you’re pulling 3 amps? The total number of amp hours available to you is going to depend on the type of AA batteries you use. If they have 2.2Ah, and you’re really pulling 3 amps, you’re going to get about 40 minutes of life, if even that. (Are you figuring a peak power draw or is this a measured draw?).
Yes, im sure the one i have is 5v because mine is marked for 5v. That’s just a stock picture from ebay of the item i purchased. I’ll be using about 240-280 LEDs. So running off of 8 AA would work with the converters and all but i would just have short battery life? Is there a better solution? i plan on using 175 as the maximum brightness for the LEDs, i avoid using white as this is mostly colorful. This is basically what im building: https://www.youtube.com/watch?v=FHJeidIXR8Y
fwiw, I usually run my wearable stuff at 1/8th brightness (or even dimmer) both to save on battery and for other people’s eyes. If you’re on the main stage you probably want to be super bright, but then you only need an hour of battery life. If you’re walking through the crowd then you’ll want something much dimmer.
-Zeke
I’ll be in the crowd + in the dark so i know i don’t need them bright at all. My goal is to run them at 50/255 brightness and 175/255 at most. My only concern is whether they’ll shine throu the cloth because they’ll be covered by black cloth on the mask.
Just as a side note, many black fabrics block a lot of light. The more “open” the weave, the more light gets through. The more dense the weave (or knit), the darker it will be. So: try it!
For power, why not look at a power bank, the kind of thing used for charging your phone on the go? Cheap, safe and easy to use.
A lot of those bricks cap you at between 0.5 and 2A power draw.
He’s got 240 LEDs running at 20%, 2A would be plenty. that was just a suggestion… I would use an RC LiPo that can deliver 35A with. 5A buck converter, but that’s because I have that stuff hanging around…
i’ll look a that. I was going to use a usb powerbank but thats not enough and i need 12v because the 6 led circle uses 12v.
And Peukert’s Law.
Fun demo/video with Gary Numan and a DieHard battery:
first this http://youtu.be/s4YsMVA8DoU
then this http://youtu.be/rHYG3QlGr8Q .
This is what I always think of when I think about battery capacity vs runtime: Peukert’s Law, and Gary Numan!
@Michal_Hipner and i need 12v because the 6 led circle uses 12v.
So use something else… http://www.adafruit.com/products/1643
Thanks,I didn’t know those exist
Oh, OK - well in my experience, 12 is unusual for this sort of ‘smart’ RB LEDs. The Adafruit rings are WS2812s, I think - 5V. I haven’t seen any rings on Aliexpress yet, but you can buy individual components and make your own, if you aren’t economically tied to the US.
Maximum current from a battery is proportional to the cell internal resistance. You’ll need to check the battery data sheet and calculate the effective resistance of the battery pack as a whole. Then use ohms law to get the peak current flow through the cell.
You probably won’t want to do that for long. On some Duracell’s we could pull so much current the battery holders melt and the paint burns off the body of the battery. Same effect as a dead short. Then they catch fire - nice (not).
That’s why the fuse was invented!!