I am trying to use 2 18650 batteries to power 288 APA102 LEDs. The LEDs require 5V, and have a max current draw of 60mA/LED for a total of 17.28A. I will also have a microcontroller attached (currently arduino micro), powering some other low-draw devices. So let's say I'm aiming to support up to 18A. Most of the time though, the current draw will be much lower.
My understanding is that I can use a buck or boost converter (depending how the batteries are wired), and outboard bypass transistor(s) to shunt additional current around the converter (with proper heat-sinking). I am curious though, are there considerations for the buck vs boost configurations? Is my stated understanding even correct? And lastly, will I need to protect my arduino somehow if I'm drastically changing the power coming out of the batteries (e.g. Strobing the LEDs from fully on to fully off)?
I'm open to alternative battery suggestions as well, but I need everything to fit in a cylinder of ~20mm, and energy density is very relevant for this project.