battery consumption between 20" and 26" fat tires

Dear all,

Does anyone notice the difference in battery consumption between 20" fat tire wheels, and 26" fat tire wheels?

I changed from much larger bike with 26" fat tire wheels with 3 gears-21 speed, and now have a smaller bike with only 1 gear and 7 speed, and 20" wheels and smaller cog.

The battery is slightly smaller on this smaller bike but by only 2amp (48v 17ah-48v 15 amps), but seems to do far worse on battery output.

Any ideas ebikers!?

Thanks so much