Adding a 12V accessory. Direct to battery?

[deejais]

I want to add a USB port to my scooter, and later maybe another small thing, well within the amps range.

If the USB port isn't the type with a light, should I just connect it directly to the battery (with an inline fuse) or should I tie it into the ignition lead or from the stator?

I work on boats usually, and have a fuse block to wire stuff into.  Thanks

[lurch]

This is how mine is wired from the factory.