One day in class I found a non-working TI calculator. "Nobody else would want this, besides it has dead internal batteries," I thought. So I took it home and decided to solve the problem. I didn't want to use more internal batteries that I would eventually have to open up the calculator again to replace, so I decided to install a AA battery pack. I cut holes in the back of the case, wired the battery pack, mounted it to the calculator, and problem solved! Now my only problem with batteries is that my friends take them out and hide them when we have tests.
I have an old casio which still uses AA batteries. I'm ok with solar-powered calculators, but I think these tiny batteries which you can only switch by opening the calculator are really annoying.
You see, I am only 15 and am currently trying to get a job. Therefore I have limited money and am too cheap to buy stuff like solar cells. Many of the parts I use in projects are from dead electronics in people's trash. I have saved a lot of money trash picking.