You develop a 3 GW power source  that can fit in a coat-pocket and it never occurs to you to market it to an energy-hungry world.
You decide to run your amazing power-suit and the device keeping you alive off the same power-source.
It doesn't occur to you that having a back-up power-source on hand would be a very good idea.
1: It's not clear if it's a generator or a battery. If it's a battery, it's one that can store at least 3 terajoules.
- You may be a superhero if