Some time ago we were notified by our Utility that our neighborhood would be turned off overnight for some maintenance. I sleep with a c-PAP machine to breath at night so I used a small inverter from Harbor Freight plugged into the car, then extension cord from car and garage down hall to bedroom. I slept well, thank you. With the Leaf in Ready mode, and no adjustments for display lights, I used it overnight. The next morning all was well, the inverter worked great, and displayed GOM went down very little. I do not remember, but it was almost nothing, maybe one or two miles range loss. Sorry to not have a better or more accurate reporting, but did not write it down, I just remember it was almost nothing.
Hope this helps.
2013 SL Metalic Slate - We LOVE our Leaf
MFG 08/13 Dlv 09/06/13 @ 10 mi
# 77 100 mile club
# 10 200 km club
2017 Tesla S 75D Pearl White
Delivered 5/16/17 @ 900 mi
Tesla Model 3 on order awaiting 200+ mile range Nissan Leaf