KR Pixel Stick brightness

[artisannm]

I believe I read something a while back that spoke to not running full amperage for color settings especially "White" such as 1023/1023/1023 as this was said to burn out the strip? I'm wondering about this as I'm using a bench meter and currently am driving my test strip at 3 amps. For other colors I stretched the values to bring them up to 3 amps for brightness. Is this approach a bad idea? Does anyone have long term experience running the KR Pixel stick at this brightness?

[Tom Tilmon]

I'm pretty sure the pixels are 5V pixels. I don't think we can arrive at harmful amperage on a 3.7V battery, but maybe I'm mistaken. I run mine full blast in every color, I haven'
t had issues. Proffie.

[RavenXp]

I think it's less do do with the amp load the strip is capable of handling and more to do with the heat generation, I think I remember someone mentioning you could generate enough heat to melt the diffusion foam if the pixels are full on with all 3 colors, but don't quote me on that as this is 3rd hand info on my part.

[artisannm]

I've been digging into things for a few weeks where I realize that a single-color maxes at 3 amps and three colors at 5.3 amps. I'm using the 21700-battery sold here at the store which supplies the typical 3.7v where I understand that the KR pixel strip is actually looking for 5v. It seems that the only way I'll see true potential out of this strip is if I give it full voltage which normally isn't possible on a battery setup. My goal is to drive a single color upwards of 4 amps if it'll do it, or to blend two colors reaching 6 amps. Worst case I could drive three and reduce power on white, where I'm looking at a day blade approach.

The question then is how best to run a dual cell setup using CFX? It would be wired in series to increase the voltage to over 7v and then I gather I need to use a Mosfet or buck regulator to reduce the voltage to the desired 5v for the strip's sake. This is where researching online is challenging to determine what electronics would satisfy this setup and still allow a max 15A pass through, matching the battery.

I've poured over the CFX manual and am not sure if the board has something built in for this purpose? There's mention of resoldering the jumper so that the board can run at more than 5v and the manual mentions use of a buck regulator but doesn't go into any suggestions. There's also the 'blade power' feature that likely requires soldering the return negatives from the strip tying into the L1 -L4, but again I got the impression that it wasn't necessary. That the blade power is tied into the data line. In my current testing I have both positive and negative lines (22 gauge) running to the strip outside the board.

Is anyone familiar with a dual cell setup that produces over 5v and how to approach wiring this up?

[Forgetful Jedi Knight]

I HIGHLY doubt you’re going to find a dual cell setup that can actually fit inside a saber. Besides, trying to feed that kind of Voltage to a single color will likely pop that color, even Green.

[artisannm]

Thanks for the quick response back. I'm working on a custom build, so fitting two 21700's may not be the biggest challenge. I've read about buck converters that step down voltage so that in this example the circuit would drive 5v, down from the 7.4v of the two batteries. The biggest issue I'm having is finding a buck converter that can pass a much higher amperage. Most are capped around 3A, which I'm already getting. I've read about shunts also, but they don't seem applicable here.

Having spoken to Erv over the course of several weeks, and not getting a solution, and while also looking at the CFX manual repeatedly, I decided to see what would happen if I removed the solder bridge and connected the lower of the three pads on the card. To my surprise after all of this searching for a higher amperage solution, running full White via amp meter went from 5.3A to ~ 6.5A. Combining two colors at full power also saw an increase over 5A. Battery voltage continues to make an impact, whereas it slowly drops so does the corresponding amperage and overall brightness.

Still, changing the solder bridge on the CFX seems to have unlocked the data signal communicating a higher potential voltage (> 5v) and consequently the strips are asking for more without fighting against the 3.7v limitation of the battery.
The KR Pixel strip itself is rated for 5v.

On a bench meter test, I saw that Red is resistored to protect it from higher voltage draw as it doesn't go above 3A, even when the bench meter was set to 5v.

It seems like supplying 7.4v reduced to 5v steady would always win out better than to start with 3.7 which drops continually. I'm still testing but it appears that using the 21700 with its higher energy density vs the original 26650 might over time slow the voltage reduction keeping the blade brighter throughout the period of battery drain.

Unless I can figure out a dual cell setup that is stepped down, it looks like modifying the CFX is the next best thing.