Solar flood light repair

In honor of Mother's day, I decided to visit my parents in PA this weekend. So on Friday evening, I took the train out of NYC to home. Now when I got to my parents' house, I heard the unexpected news that our solar flood-light had been out of operation for a week. That sturdy light had been working for the last 2 years, though with a gradual decline in performance. Over the last 4 months, only 2 of the 4 LED lights on the lamp had been working. A solar powered light is an incredibly efficient(and relatively expensive) piece of technology. Thus before we throw it out, it's worth at least one attempt at repair. So I put on the engineer hat and dis-assembled the flood light. The internal workings of the light are remarkably simple. The device is composed of basically 5 modules:

1 Photo-voltaic panel

1 Circuit board

1 Power pack holding 2 Nickel-Cadmium AA batteries

1 Plastic mount holding 4 LED lights

1 Light sensor

The PV panel collected solar energy and converted it into DC electricity. The energy is channeled through the circuit board to recharge the batteries during the day. The light sensor mounted at the exterior of the device would send a signal to the circuit board when the amount of light hitting it falls below a certain level(like during night time). The signal from the sensor basically tells the LED lights to begin drawing energy from the battery pack and converting that energy back into light. So what had gone wrong?Well, it appeared that the PV panel itself was protected by a thin slice of hard plastic. The ultraviolet rays from natural sunlight had basically broken down the top layer of that plastic, making the panel a bit opaque. This had the effect of significantly reducing the amount of solar energy the panel could capture. Additionally, some dust and mud had gotten onto the light sensor. This had the effect of making the solar light turn on earlier than necessary. Thus, the device was forced into collecting less energy during the day and using more of it at night. Now batteries tend to heat up when stressed for power, and at higher temperatures, the alkaloids within them become much more corrosive. After a period of time, the chemicals had eaten through the metal walls of one of the batteries, thus rendering that battery useless and knocking out 2 of the LED lights. Apparently, in the last week, the remaining battery had failed as well, making the light completely inoperative.

The solution was fairly simple. I replaced the dead batteries with a new set of rechargeable ones. That brought all 4 LEDs back online. Then I cleaned up the exterior of the floodlight, paying extra attention to the light sensor. After cleaning it, I tested the sensor under an indoor lamp to make sure that it was properly turning on/off the LEDs. The PV panel took some work. I used fine grade sand paper to clear off the top most layer of the hard plastic cover, until the PV cells were fairly transparent. I then took a very thin sheet of cell phone screen protector, and pasted it onto the hard plastic. Now instead of the plastic cover, the sheet will take the full brunt of the Solar UV damage. And when that sheet breaks down, we can just replace it with another one. After that, everything was working like a charm. I set the floodlight into it's proper place in our front yard, and it was shining gloriously again!