The following is a battery box build I wanted for field operations, with overall dimensions at 12in x 6in x 7in and the whole unit is about 12lbs, I started with a fairly good-sized ammo box I acquired at a hamfest I cannot even remember how long ago. My first attempt was with a salvaged lead-acid UPS battery, but I found it too heavy to be practical, and the cells were not in great shape. I did some reading on Lithium Iron Phosphate and decided to give that a try, especially since a 20aH was just about the right dimensions. The very first iteration was with the triple bulkhead mount outlets similar to Powerwerx, but definitely a Chinese knock-off. When I bought that panel a few years ago, it did not have an Anderson PowerPole module, but I was able to locate a 3D Print STL file and printed my own. Since that time, I see Powerwerx does carry them now. I added a power button for the USB power module since it was in an "always-on" mode. I found a step-index drill bit sourced from Harbor Freight was sufficient to bore through the steel casing. The next iteration was to put in a voltmeter and ammeter. The units I ordered from Amazon were larger than I anticipated, so I had to go back and get a 70mm carbide hole saw (so yeah, I have one of those now). I added a powerpole "bus" to eliminate the wire nuts and electrical tape, making it feel a bit more solid. I padded the battery with some foam packing material we get tons of at work every time we get a new computer in and secured the internal components with urethane glue.
Fulton County Amateur Radio Club, serving Fulton County since 1954