I picked this rusty old thing up, as-is, from someone for $5... I figured it had at least that much worth of copper in it. After sitting in my cellar for a few years, I decided to drag it out to deal with a chronically dead battery.
The first picture is the before picture of the wires... yikes, bare copper. That's really good quality stranded copper though, so I did up the "electrical tape special"... it took two rolls, see center picture for the finished product.
Surprisingly, it works like a charm. 6, 12, or 24V battery settings, as well as slow automatic or fast manual charge. The gauge seems to work as well. I assume this model would have been owned by a mechanic or an auto parts store back in the day.
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The only thing that I cannot figure out; what is the "polarity protector safety light"? It was lit the whole time that I charged the battery. I had the "red" clamp on the positive, and the "green" clamp on the negative. The battery charged fine, so I don't know what was up with that. The body was not otherwise marked which terminal was which.