Flux, very good points, my old 32v Dunlite which I use at 24V at times causes me much frustration. If not for the nostalgic value I would replace it with another duel rotor, without a reasonable understanding of how they work (therefore how to fix them) they are as Flux said, old technology.
My Dunlit is capable of 60v open circuit terminal voltage, but I don't believe it would perform well on a 48v system.
I have several awaiting restoration, sourced from similar ads, but now believe I would have better spent my dollars on magnets.
allan down under