You can always roll your own with 18650 batteries and MP1584EN converters. This has 23.2MA at 16V as the main supply (has to be 3v higher than the buck down target) and the converter has 96% efficiency. Basically I go a couple months without recharging. It has two converters and 16 barrels because I wanted to see how long it would run with a huge load (not shown). Answer: who knows I got tired of waiting.
I have a more eloquent layout with fewer batteries and ports that I have in the dev stage, 'cuz this was total overkill, lol....
View attachment 39654