I don't want to put it down too much simple but let's try:
where "P" is power,"V" is voltage and "i" is the current. (Units of measure [Watt], [Volt], [Ampere] )
if we keep "i" costant, we have:
11,1 * i > 7,6 * i
e.g. 11,1 V * 1A = 11,1 W > 7,6V * 1A = 7,6 W
The result is that a 11,1V battery can spin the lens motor phisically faster than a 7,6V battery,
if there are no differences in circuits, I mean, amplificantions, cuts, stabilizations etc etc etc, and obviously the lens must be designed to accept a certain range of potentials.
Things are not so simple, but this is only for exemplification purposes.