Hacking a Device to Use Batteries – Why Is It So Hard?

As you all have probably noticed, there are two mainstream ways that electronic devices are powered– by plugging its cord into a wall or through the use of batteries. But as our world becomes more mobile (in multiple senses of the word), it makes a lot of sense that a variety of devices are now using batteries as their source of “wireless” power. However, there are still quite a few things out there that need to be plugged into a wall. While this makes sense for large devices like a welding machine, you’ll still find most table top fans need to be plugged into the wall socket. What is preventing this change from happening?