Power management for a traffic wand esp32C6 Xiao, 2812b

[peekpoke]

Hi all,

Third project here, learning a lot about power supplies, regulators. This is a fun project to build on a normal simple traffic wand

I want to add features like:

1. Smooth LED line instead of dotted,
2. Program patterns and colors to be set with a switch.

I'm thinking of the following hardware:

1. 1m of COB LED individual address with WS2812b: https://a.aliexpress.com/_mtQdfiR
   a. 18w at 5V over 240 LEDs. (3.7A!) I'm guessing I'll need to cut that back a bit.

2. Xaio Esp32-C6 with built in charging,

3. Li-ion 18650 cells,

4. Using an old wand for the structure.

Here are some requirements:

1. Programmable
2. Battery endurance approx 3 hours
3. USB C port for charging, software updates,
4. Batteries must fit in the handle. There's room for 2 18650s
5. Maximum efficiency due to the lack of battery space and high number of LEDs.

The point I'm at in design is how to power both the esp32 and the LED strip.

I've read about linear vs switched, LM317, AMS1117, L78XX, HT7533, LM1578a, and lastly the
XL6009

Currently I'm thinking of boosting the batteries in parallel to 5V for the LEDs, and regulating for the esp32. Does that give more mAh than bucking a 2S?

Is there a generally preferred approach to this scenario?

[xfpd]

@peekpoke

Smooth LED line instead of dotted,

I did not know COB LED came in WS2812. You can try add diffusing (translucent) material around the WS2812... to see if you can make is smooth.

@peekpoke

Program patterns and colors to be set with a switch.

Very possible. Here is an example of selecting a pattern with a button: lightningBolt - Wokwi ESP32, STM32, Arduino Simulator

@peekpoke

Battery endurance approx 3 hours

Depends on capacity of power supply.

@peekpoke

Does that give more mAh

Nothing is free. Increasing voltage potential decreases current capacity (for power to remain the same). Will the WS2812 require more than your power supply allows over three hours?

One way to extend the charge of your battery is to lower the maximum brightness of the WS2812. In darkness, half-bright is quite bright. Daylight will wash-out the colors under half-bright.

[TomGeorge]

Hi, @peekpoke
Nice project.

Have you Googled;

arduino lightsaber

Some interesting projects that might help.
The fact that you have the original hardware means you are halfway there.

Tom..

[sonofcy]

Do NOT under any circumstances put 18650 Lithium cells in parallel. They stand a very high risk of exploding or catching fire.
Do your math on the LEDs power requirements.
If the batteries are 2x3.7Vx2500mAh then you have before conversion losses 18,500mWh or 18.5Wh which means maybe 1 hr of use. Since LiPo or LiIon is for all practical purposes the most energy dense batteries available to us this means at least the equivalent of 6 18650 are needed.
Another option is a larger (see pic) LiPoly pack like RC modellers use carried on your body, either belt or back pack and a cable connects them to the wand.
I am attaching 2 pics of a 57.72 Wh battery, the 2nd shows dimensions and a link to the charger you need. https://www.skyrc.com/ I think the S100neo would be a good fit. That charger CAN do parallel, that is what the small wires (JST/XH) are for, it's called balanced charging.

[peekpoke]

No idea why I didn't think of that connection! Thanks!

[peekpoke]

Thanks for your input.

I wonder what I really have here. Part of the part description is "WS2812B SK6812" Am I correct to say this item relies on the SK6812 instead of the 5050? Assuming I know what I just asked. Is this relevant?

Perfect find on the Lightning Bolt project! Thanks.

[peekpoke]

@sonofcy

this means at least the equivalent of 6 18650 are needed.

Thanks! I was doubtful about my calculations.

Yup, I need to accept less LED density.