Discussed (a bit) at the time:
The Mystery Monk Making Billions With 5-Hour Energy - https://news.ycombinator.com/item?id=3572596 - Feb 2012 (3 comments)
Also:
Creator of 5-hour Energy Wants to Power Homes with Bikes - https://news.ycombinator.com/item?id=10357663 - Oct 2015 (20 comments)