on a spad trainer w/ a gms .47 i have gone through 2/3 of a gallon (at half throttle most of the time) before i drained my batterys to the limit (they were starting to slow down when you wiggled all of them, yes i know i shouldnt have done that, i was a noob at the time)

point is you really dont need more than 800 nicd in simple 4 servo models. i prefer 1400-1600mah 6v batteys but you really dont need them

also towers prices on batterys are insane. look here
http://www.all-battery.com/6vnimhbatterypackseries.aspx 6v batterys
and
http://www.all-battery.com/48vnimhba...ackseries.aspx 4.8 v batterys