Solar Powered TI-82?

numlumps asks: "Recently, my batteries for my TI-82 ran out of juice. Since there is no environmentally friendly way to dispose of batteries in my area, I figured, why not do away with the things altogether? I figured if it were possible to power my calculator with solar power, I'd never have to buy batteries again, nor would I have to worry about toxic chemicals from old batteries leaking into groundwater and so on. Has anyone built a solar power kit for TI-82 and similar calculators? If so, how do I do it without ruining my calculator?"

Comments

rechargeables?

[xjesus]

Have you thought about rechargeables? With the latest developments in NiMH batteries, they actually last over twice as long as the old rechargeables. They also eliminate the 'memory' effect; so you can charge them whenever you want. Here's a link to a place that sells AAA NiMH batteries, a little under $2.50 a piece. You can get a charger from the same place starting at $8. They also have a Solar powered charger... you might be able to rig that to your Calc and never have to remove the batteries! (just leave it in the sun from time to time).
As for retaining the memory on the '82, I know that the 85 has a small watch like battery to help keep your RAM happy, so you don't loose those progs. If you ran soley on solar power this tiny battery would probably not last too long (unless you left the calc in light all the time).

Good luck!

This is what I would do...

[cr0sh]

If I had one of these calcs (my standard sci calc TI something or another works fine for what I need it for - but I understand others have different needs)...

From what I have read, these calcs take 4 AAA batteries. This would probably be a 6 volt source. I would hook up a connector to the battery compartment, wired in parallel with the batteries, and use NiMH batteries as suggested, and charge them from a charger. This would be a very practical solution, and not too hard to implement.

Now, add the solar cells panel - go down to a Harbor Freight or Fry's Electronics (HF will be cheaper, but work with what you have), and pick up a 12 volt car battery solar charging system. These systems generally consist of a 12 volt panel of solar cells, sometimes two or three wired in parallel to up the current for charging a car battery. Get the smallest one you can.

Once you have the panel, you will need to open it up, and rewire the cells to be two (or however many) strings of cells, wired in parallel, each string of cells producing 6 volts. You essentially want enough current to charge the batteries, but not too much to fry them (by quick charging them for too long). If you want to find the current output, wire a 1 meg resistor as your load across the contacts, then check the voltage across the resistor, I=V/R (I may be wrong here - but this stuff is easy to look up, and I know I am close).

Most solar cells typically generate only .5 volts or less per cell, at typically 10-30 ma of current capacity. That would be 12-15 cells per string. If you want to make you own panel, look for solar cell grab bags - the cells migh be broken, but they are more than usable still...

I support the EFF - do you?