[maxxdude1234]

Serum, let me show you some formulas:

V=IR ; potential difference (voltage drop) = current x resistance (a constant)

Hence voltage is directly proportional to current.

P=VI ; power (watts) = current x voltage

If we re-arrange the first formula to give ; I=V/R , and substitute this into the second forumula we get;

P = V x V/R or P = V^2R .

Again say R is a constant, if voltage doubles, power will quadruple. This happens because as V doubles, I doubles, and P=VI, so P quadruples.


So if 18 cells are used rather than 12, this will give a ratio of 1.5:1.

1.5 x 1.5 = 2.25, so theoretically power will increase by 125%.

Hope this clears things up


*PS. To answer your last thing, adding more cells will decrease runtime, because more voltage = more current. This can be combated by a higher turn motor that will draw less current at a given voltage (in other words its resistance is higher), however the sacrifice will be power.
In theory a 7XL on 20cells will be more powerful than a 12XL on 20cells. OF course all this is providing the batteries can provide the current.