The extra piece I printed for the screen also works as a mock bottom piece to get the full size of the console.
I realized there that it needs to be made at least 1mm thicker because the 18650 Li-Ion battery cells won't fit beneath the screen otherwise. The batteries are what is really determining the max thickness of the unit and it would be made more slim and sleek if the LarkBox used 5V instead of 12V for power. 5V makes it possible to use a single cell instead of three, so I could use a LiPo there instead of the Li-Ion.
The three cells are from the 12V power bank which has an additional board to distribute both 12V and 5V power. The 5V can be useful to power the CPU fan independently. I could not find the exact battery model but it has to be approx. 2600 to 3000mAh for each cell, if total capacity is 30 watt hours.
I also have a massive 10000mAh LiPo that I can use, and does work well with my Atom-powered stick PC. I also have tried using a boost converter for 12V input to the LarkBox. However, the LarkBox didn't like it. The PC would power on, and get to the boot screen logo, but then restart, and go through that boot loop over and over again.
The power might be spiking during the boot sequence which the LiPo doesn't like. The spec of the LiPo did say that it is limited to 3A current, which multiplied by 3.7V means you can only hope to power up to 11.1 watts. In an article comparing the power draw of a Raspberry Pi 4 to a Celeron J4105, the Celeron uses twice as much power when all 4 cores are in use. And the Larkbox uses a J4115 a higher clocked version of the Gemini Lake family.
Somewhat regrettably, had I bought the very similar GMK NucBOX the battery space issue could be solved more easily because since that uses 5V DC instead of 12V. All you would need there is a single 3.7V cell, negating the need for a balancer circuit, and with a more modest boost to 5V power everything in the console quite easily.
