If i run 12 12v batteries in series to get 144v and the batteries are 100 ah. Does that mean i will only have a total of 100ah at 144v to use? If i lowered my voltage and and raised my AH by running some of the batteries in parralel, wont my range still be the same since its a lower voltage and its going to pull more amps to get the same rpm out of the motor? Im a bit confused. 
range is based on Wh/mile…
watt hours is volts times amps, 144V and 100Ah is 14,400Wh.
If you lower the voltage and run 200Ah and 72V, its still 14,400… The controller does the power conversion… so it can run the motor at 72V and give it 200A, but only draw 100A out of the batteries at 144V.
Basically what im wanting to i know is if i will have the same range if i have 100v and 50ah would i have the same range as if i had 50v and 100ah considering Watts=volts.amps and Watt hours equalls my range.
essentially yes…
but if you draw high amps (lets say 200A) out of the 50Ah system, the batteries will NOT like it… but the 100Ah batteries will be less effected. Its called the peukert effect. If you draw higher currents, it decreases the total Watt Hours of the battery.