No, not that bad
I bought a USB charger type socket with built in voltage meter about a year ago and never got around to fitting it until this week.
Checked, double checked and braced myself for the worst and drilled the 30mm hole in the dash. Turned out to be a good guess for the positioning
So proceeded to run the main feed to the battery and a relay to be on the safe side, and spliced into the horn feed for the ignition 12v. Connected up, looking good.
Then start the bike .... little voltmeter zooms up to 15.8V and starts flashing like an exhibitionist on columbian marching powder
First thought is that the reg/rec is fried and reached for the multimeter in the toolbox.
Woohoo! panic over, turns out the usb voltmeter seems to be set up for Chinese volts which are obviously different from ours. Only problem now is I have a 30mm hole in my dash. Luckily the various Chinese factories all think that 30mm is a suitable sized hole for all the usb chargers so I ordered a few from Amazon to spread my luck.
So three days later I finally finished and it works, for now anyway.
Moral of the tale, test your cheap electrical thingies work before
you drill the hole.