I have used a different version of this concept for sometime now. This version is more portable due to the weight saving Lithium Ion Cells.
36-2000 maH Lithium Ion Cells 4s 9p
16.8v @ 18 aH
The goal of this pack is to have a source of power that can be converted to voltages from 2v to 40v as well as have control over the amperage. The DC-DC Buck/Boost Module used is capable of adjusting the 16.8v out of the battery pack to meet those needs and with the help of the fan and the lid open, it will handle nearly 6 amps (lid can remain closed for power needs under 3 amps).
One of the main purposes for this pack is to boost the voltage up to 20v @ 3amps to recharge my Lenova Yoga Pro 2 Laptop while staying at my off-grid cabin. I spliced into my laptops power cord after the transformer (DC side). From here I can hook the Lenova specific connector to a pair of Anderson Powerpoles directly to DC-DC Buck/Boost Converter.
Alternatively, when I am near 110v house power, I can now use the laptops power supply to recharge my battery pack by directing the powered end in the DC-DC Buck/Boost Converter and bringing the voltage down to 16.8v @ any amperage I wish to charge my pack.
From time to time I also find myself using this pack as part of a test kit. In the picture below are several types and styles of connector with one end using Anderson Powerpoles.
With these accessories I can power many consumer battery operated devices for testing, emergency power, or charging. This pack has also come in handy to jump start a slightly dead car battery. The 10 amp Battery management system and the 10 amp circuit breaker limit the current but the pack does a great job of charging a car battery at 5 amps for a few hours.
I can also charge the pack from a running vehicle with use of the male cigarette adaptor. Also, I can add the female adaptor and power 12v car appliances when needed.
A solar panel could be added for charging but I have yet to test whether a solar charge controller would be needed or if the DC-DC Buck/Boost Converter could handle the dynamic voltages of a solar panel alone.