A common question I get asked is how I test the capacity of lithium cells and power banks. It's pretty straightforward due to the incredible charging efficiency of lithium cells.
If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:
http://www.bigclive.com/coffee.htm
This also keeps the channel independent of YouTube's advertising algorithms allowing it to be a bit more dangerous and naughty.