Basically if you pedaling faster or going Downhill while using the cruise function, the motor won't have to work as hard to keep the original speed/power.
You will use much less amperage that way.
The AH rating is just how many amps per hour you're using.
Use 5 amps for an hour and that 5ah
if you use 4 amps for 2 hours that 8ah
the rating on your battery is done in amp hours
so if set for 8 or 9 mph, let's say the motor would pull normaly 5 amps ( just an example) on a flat road. If you start pedalling then the Motor won't have to pull a full 5 amps, maybe only 2.
So if you ride for 1 hour at 9mph, if you don't pedal you'll use maybe 5ah's (5 amps for 1 hour).
If you pedal with it and go a little faster, the motor won't have to work so hard and will only draw, let's say 2 amps for that hour using only 2ah (2 amps for 1 hour).
Hope that helps answer your questions.
P.S. Nothing about that has anything to do with regen.
Regen has to do with while your braking the motor changes from using electricity FROM the battery to power the motor, to using the motor as a generator to provide electricty TO the battery.
Of course there is a more technical explanation about regen but that's the generic use of it.
