Micro-AE experiment

I've not had the available facilities to do much in the way of alternate energy stuff, but a happy coincidence made an experiment possible.

Some time ago, I bought a cheap AM/FM radio which claimed you could power it 3 different ways:

• With solar energy (its lens across the top proclaims "SOLAR POWER").
• With the little crank-generator on the side.
• With external or internal 3 volt power (two AA batteries, not included).

This radio initially charged itself and ran on solar power for some time, but its endurance shrank until it would not run on stored solar power at all and could eke out maybe a minute after a good amount of twisting the crank.  I opened it up, and found its battery was a pair of NiCd button cells mounted to the PC board; not exactly the best storage system, and probably the cause of its failure.  But it didn't charge all that quickly to begin with, and I wondered what I could do with this to make it useful again.

Then a busted solar-powered driveway light fell into my hands.  The plastic top and electronics were still intact, so I appropriated it.  It has two AA NiCd cells and a solar array about two inches square on the top.  The cells are in spring-loaded holders which make them easy to remove (no solder tabs or other difficult stuff).

To prevent the cells from discharging at night, I have to remove one from the holder at dusk.  But they fit into the little radio just fine, and I've been listening to it for several hours now.  Am I depleting the cells more than tomorrow's sun can charge them?  I suppose there's no good way to find out except to keep testing them.

Aside from being a useful test of an otherwise-useless device as a solar AA charger, it's an interesting little bit of consciousness-raising.  If I can find a good way to mechanically mount the solar cells to the radio and reconnect the battery circuit so it uses the AA holder instead of the button cells, I could use this unit as either a long-playing solar radio or a hand-crank charger for just about any AA rechargeables.  But the hacking potential of this unit will have to wait until I've built my rotating Scrabble board holder and some shelf-mounting brackets for my windows so I have someplace to put my houseplants.  Got the wood and the tools, now I just need the time....

Update 10/17 21:43  One gray day was all it took to reduce the playing time to 20 minutes or so.  It's supposed to be sunny tomorrow afternoon; I'll tell you how it goes.

Update 10/19 21:43  The radio ran for an hour and a half last night after a sunny afternoon; the batteries still had zing left.  I put them in to charge again this morning, and I've been using them for about two hours so far.  Still going strong.

As a cheap battery charger and recycling method for a busted piece of outdoor ornamentation, this is mighty hard to beat.

¶ 10/17/2006 12:50:00 AM