Dewalt battery powered inventions
I'm not very savvy when it comes to most things electrical, but have a question about (mainstream) rechargeable battery powered inventions. In my case, Dewalt 18v batteries, but for arguments sake, it could cover a slew of rechargeables.
I have at least a dozen Dewalt 18v tools and accessories. I've had most of them for years and only the 2 most well-used tools have failed (and been rebuilt). So I love the reliability. I 'round-robin' my 6 batteries (mix of the older style XRP and the new Li-Ion), I've yet to have a battery fail and all still hold a decent charge - the oldest XRPs are going on 7-8 years old.
I often use my (2) dewalt lights I have as light when the power goes out in the house or when I spend a few nights at the race track (tent camping, but not roughing it like out in the middle of the woods). 3-4 batteries typically do the job for a weekend. I'm on the fence about buying a Dewalt (charging) radio, but it doesn't seem like it will charge via USB when it's running on battery power....
...which leads me to my main (ignorant) question: Why don't we see inventions that can be powered by main stream rechargable battery (reliable, safe, readily available, and owned by many people already)?
A couple examples include:
A device to charge small electronics via usb (Cell phone, tablet, etc). Smart phones can do so many things now, being able to charge it with existing batteries would make them even more universal (http://www.huffingtonpost.com/steve-cichon/radio-shack-ad_b_4612973.html )
A small fan, something pretty portable. (yes, I know I could probably rig something up with my drill, but having a dedicated fan would be nice)
A small water pump. (again, ignorance comes into play here) Not sure what kind of pressure/flow rate is possible, but having it connected to my rain barrels to increase the pressure over my current gravity feed setup would be nice. I'm not looking to pressure wash, just want to be able to have some more pressure. (minor update: An ebay search yielded one for sale, looks like I'm no pioneer here)
I should have wrote the others down, I recall having a few more ideas.
Any input from a knowledgeable person on the topic would be appreciated.
And for those that may argue that buying these devices and using standard batteries (AA, AAA, C, D, etc) would be a cheaper investment. You're right! (IF you didn't already have a bunch of tool batteries, which is my point)