Almost every place that I have seen solar lights carry the replacement NiCads for them. If you have a NiCad/NMH charger that has a refresh cycle I would try that first. See if they're recoverable. I bought some solar lights just for the solar cells and photocells and have taken a quick look at the voltage going into the battery and I'm surprised that the solar lights work as well as they do. They need as much sunlight as possible, so if yours are in a shadow for part of the day, then that will work against you. Make sure the solar cell doesn't have too much dirt, dust, debris on it. I bought two different types of solar lights and found out that the solar cells for one only really generated a charging voltage when there was infrared light present. The 2nd type had a charging voltage with or without infrared light. If I were to buy and actually use a solar light for outdoors, I would fully breakin and charge the battery on my NiCad/NMH charger before installing the lights. If you do need to get new batteries just remember to recycle your old NiCads.
