Columbus had one like that on the Mayflower. He used a wind generator to charge up his lithium cell phone batteries. The meter would tell him when the batteries were fully charged.
I too like finding a second use for many things. As soon as I get rid of something, I'll need it.
I have an old ammeter like the one on the left. I have 2 wires connected to it with ends that look like the ends of a large flat car fuse. When there is a short, I install the ammeter in place of the fuse. Helps find the shorts that way.
thanks for sharing.