I went the LiPo route purely because I will always have a bunch of LiPos with me in the field & even have a permanently wired XT60 output in my car, whereas I may well not always have a USB power bank with me. It also means that in a tight spot (like when you’ve forgotten to pack a battery for the GCS!) you can just use one of your flight packs. Because the GCS is a fairly low power draw application you can even use a flight pack that you’ve already flown, which no longer has enough charge to handle the high current draw of a copter/plane without sagging too much, but can still trickle out a few hundred mA for the GCS for quite a while.
When choosing a regulator, pay attention to whether they are buck/boost or just buck. The cheap LM2596 that I used are just buck, with the datasheet specifying that you need to input at least 1.5V above the desired output voltage. When experimenting with my bench power supply & varying the input voltage, I didn’t encounter any problems with my 12V monitor even as I reduced the voltage below 13.5V to simulate a 3S LiPo, or a car battery without the alternator running, but your mileage may vary. I suspect that the field monitor I’m using doesn’t actually need 12V, as it is primarily intended to run from a standard 2 cell camera battery which will only be 8.4V fully charged.
I finally had a chance to use mine today, on a very bright day with almost no cloud cover. The photos don’t really show it well (the screen looked much brighter in person!) but my decision to recess the panel down to the case’s standoffs so the case itself would act as a sun shield worked very well - I had no problems with brightness or reflections. The screen is really a bit too small, but as I think I’ve already mentioned I chose it because it’s what I already had! I was able to alter parameters in the parameters list with the copter on the ground just fine, but glancing down to see gauges mid-flight wasn’t particularly easy - but then maybe mounting it on a tripod at eye level would help with that?
I have no plans to make any further changes right now. I like that in its current form it is a fairly ‘generic’ device which can be used for many different uses by connecting the appropriate peripherals by USB, rather than building in controls that only serve one specific purpose.
It is the standard raspbian/raspberry pi os. The guide linked in the first post is probably a little out of date now, but the basics steps are probably still the same.
