Several years ago I bought a box of eight solar lawn lights and installed them in my backyard. At the same time (or soon afterwards) I bought a second box of identical units and stored it away for replacement. I guess I expected their lifetime under the southern California sun to be short, and that I expected difficulty in finding exact replacements later. It turns out I was right on both counts and I'm happy my past self left me a box of replacements. My back yard has been dark for a while, but now I can try to bring these lights back online.

The functional evaluation steps were:

  1. Fully charge a NiMH AAA battery cell for testing.

  2. Remove a lawn light's solar+LED module with a 1/4 turn counter-clockwise. The module may break apart if plastic has turned brittle.

  3. Open battery compartment door. The latch may break if plastic has turned brittle.

  4. Remove old tired NiMH AAA battery cell for proper recycling.

  5. Inspect battery compartment and clean any corrosion built up on terminals.

  6. Insert charged NiMH AAA battery cell.

  7. Cover solar cell, the LED should turn on and illuminate.

  8. If the LED does not illuminate, the circuit board is dead and the entire unit must be replaced. If the battery compartment door is in good shape, keep the door for use with another unit.

  9. Expose solar cell to sunlight, the LED should turn off.

  10. If LED does not turn off after 5-10 seconds of direct sunlight exposure, the solar cell is dead and the entire unit must be replaced. Again the battery compartment door, if in good shape, can be used in another unit.

  11. If all tests pass up until this point, install one of the salvaged NiMH battery cells and reassemble so the battery can charge via solar power.

Using these steps I determined out of the eight original units, half of their solar cells had failed. A fifth unit had a functioning solar cell, but its structure was brittle and broke apart when I removed it from the light. That leaves three of the original units still functioning well enough to get replacement NiMH batteries, one of them also getting a replacement battery compartment door from one of the dead units. New units replaced the failed lights. Now I have back yard night illumination again, and I still have a few new-in-box replacement units ready to go in the years ahead. I'll reevaluate my lawn light situation once they run out.