I am trying to build a Tron disc using a Proffieboard v3 and neopixel LED strips. I was following a documentation that did not work and I am stuck.
The parts I am using:
Proffieboard v3
SK6812 LED Strip trimmed to 97 LEDs (originally 144/meter)
SK6812 WS2812B MINI 3535 trimmed to 68 LEDs (also 144/meter)
UltraFire 14500 Battery 1800mAh Li-ion 3.7V (first attempt wired 5 in series, second attempt 4 total, 2 in parallel stacked in series on another set of 2 parallel)
the hubbie proffieconfig showed I should attach a 470ohm resistor to the data pin on one of the blades, and not the other. Another documentation told me to use a 330ohm, and the documentation I followed told me not to use any, they weren’t needed. I did not use a resistor in any attempt and am afraid to try anything further without frying another board.
This is exact spot on the board that has fried each time, at least this is the part that lit up and fizzled:
*Or goto something overall with the proper range of amperage and voltage. There’s only a sum total of “x” LED’s that the board should be able to animate at a more reasonable power level. An 18650, 15a, 3000mAh should be able to fit into the Tron disc IIRC.
You can have as many batteries as you like, but they should all be in parallel, no series! Connecting batteries in series will increase the voltage, which will fry the proffieboard.
I was following some else’s schematic. I clearly have no idea what I’m doing or how to calculate the proper voltages required. I tried to power one of the Proffie’s off a single battery and it didn’t power on. It was either a bad connection on my end or maybe an underpowered battery? I do have some 18650, 15a, 3000mAh batteries I can test. I should only need one?
I want to understand because I have future projects I want to make. The LED strips need 5v, right? Is the 18650 providing 3.7 going to be enough? This was why I thought to stack 2 to get over 5v. In theory I can power the board, and 2 LED strips off just one 18650? Do I need resistors in this set up?
One of those would be enough. You can use more, but only in paralell.
No, they are rated for 5v, but they work fine down to about 3.5 volts. Below that blue starts getting weaker, but it still works down to 3 volts, and by that time it’s time to charge the battery.
Yes.
Voltage isn’t one of those “more is better” things.
For voltage, you have to stay within the specified range, which in this case is 3.0 to 5.5 volts.
Battery current is a “more is better” thing. Regardless of how many amps the battery can provide, the board (or any other circuit) will only draw as much as it needs.
Not just in theory, people do it all the time.
Note that not all 18650 are born equal. You need one that can provide at least 10A (15A is better) to be able to provide current to all those batteries. If you add more batteries (in parallel) the only difference will be that the battery will last longer.
You need resistors to protect against shorts, but that’s different from the type of resistors needed to drop voltage in a regular LED setup. For neopixels, each pixel already contains the current limiters needed, so no such resistors are needed.
I am trying my hardest to understand this. I will be honest, it sounds like witchcraft to me haha. But I will keep at it, I promise.
I have a new proffieboard arriving on tuesday. In the meantime I am designing the chassis of the disc to support 2 18650 batteries in parallel. I’m doing 2 for balance reasons so their weight is opposite each other in the disc.
I have a usb-c extension port and battery recharge module. I have wired these with 30awg wire as that is what the products recommended. The battery terminals I wired with 20awg gauge. Should I wire everything in 20? Or am I safe using 30 in some areas?
The flexibility of 30 is great for the small area I’m working with.
Here is a handy chart which specifies what wire size you should use.
Note that thicker wires is always ok.
Also note that this chart is a bit on the paranoid side, and going down one or two sizes is generally fine, since the wires we use are always short.
Of course you need to know how many amps the wire will carry to use this table. Here are some guidelines:
Data lines: 0 amps
Buttons: 0 amps
Blade +/-: 10 amps
Neopixels: 0.03 amps per pixel
Most regular small LEDs: 0.02 amps
USB charging: 1 amp
Speaker: 1 amp
It works! Thank you all so much! Now I get to figure out how to code this thing. But it powers on, charges through usb-c, and allows me to configure it without taking it apart. Both LED strips and the speaker are working. You guys are awesome!
