It uses a 1.5 amp fuse. My guess would be that nominal current draw would be less than 750 mils. I don't think it is significant. Current draw is going to depend on the internal battery voltage. The internal battery is being charged while the unit is powered up.
I would have thought that the fuse size would be easier to find on the Garmin website, but it is somewhat hidden... however if you want an official confirmation of Mel's number, I found it on page 143 of the manual, here.
