I was thinking of doing the same thing. I went to Wally World a few weeks ago and discovered some of the solar-powered walk-border lights did have NiMH cells but most had NiCd. I don't like NiCd. It recently got unseasonably cold here and three of four solar lights (different Chinese imports) all with NiCd cells failed to illuminate at night. That could be a coincidence I suppose, but I think I will try a NiMH cell this weekend. I think Best Buy and Radio Shack sell them here in the United States. I use the larger AA size in my portable Elecraft KX-3 transceiver and they give me good service there, so the chemistry is good.