If you want to quadruple your amp hours without modifying the hardware, just treat 25% of the voltage gradient of each battery as your unit of measurement.
Alternatively, since this is USB-C, and we assume the marketing copy is honest, use the max voltage USB-C can deliver: 20v.
So, draw 20V from this device and measure the amp hours it outputs.
If you want to quadruple your amp hours without modifying the hardware, just treat 25% of the voltage gradient of each battery as your unit of measurement.
Alternatively, since this is USB-C, and we assume the marketing copy is honest, use the max voltage USB-C can deliver: 20v.
So, draw 20V from this device and measure the amp hours it outputs.
Wh is really the only sane way to go.
Lithium NMC, which I think is the most common, is 3.7V. Lithium iron phosphate, which some power packs do use, has a nominal voltage of 3.2V.
And LTO, which is what I actually want, is 2.3 - 2.4 V.