Yes.If there is power your nose will glow and your ears will rotate.I wouldn't have the first clue how to operate one of those.
Can't I just spin the wheel and put my tongue on the hub contacts?
GC
A torch bulb and two bits of wire will suffice for checking the dyno output.
Could it be water/condensation in the hub shell ?
Don't let WD40 anywhere near the seals of any hub or BB.I don't think so. The bike's only a couple of months old and is always stored either in my garage or office bike shed. When I wash it I use muc-off and rinse with a hand-held water spray, not a hose, then wipe dry with WD40 treated paper towels.
GC
Don't let WD40 anywhere near the seals of any hub or BB.