Hey Star. When you unplug a cigarette style power outlet, there is no load at all. When you unplug a USB device from a USB adapter, I believe there is still a bit of parasitic drain from the electronics inside that are converting 12v to USB spec power. That USB outlet in the top case is not fused separately. There is a 12v power distribution supply that runs around the back end of the bike, powering things like the plate light, tail lights, etc. Everything in the top case comes off of that. I think it's fuse F1R. So, you lose a lot of things if that fuse blows, not just the USB adapter.
BTW - that interior light in the top case, does NOT care if the lid is open or closed. As long as the key is on, then that light is on.
Now, if you really wanted an always on power outlet, you can install that accessory into the frunk. Just get any auto style power outlet of your choice and install it in that hole in the left side ( left as you’re sitting on the bike) of the frunk that has the rubber plug in it. It's behind the liner. Then remove the battery - for easier access - and look for these wire connectors in the upper left side of the battery area. Again, left as you’re sitting on it. Just push them onto the back of the power adapter. You might benefit from an extension harness for the adapter. Then that power adapter is powered from the F6 fuse swap and you could make it always on if you wanted.
Or, you can utilize the GPS power outlet and install one of those nifty handlebar mounted power stations. Many options.
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