comparing unequal data sets

#1
I would like to compare the results from the tests I proformed. here is a link to the data

The research project involved the application of a PEM Fuel Cell system and its actual performance in the operation of a robotic buggy in a variety of settings and terrains. The goal was to increase the battery life 300% in actual application. This was accomplish through four case studies:

Case 1. Surface type: Linoleum, Topology: Flat Distance per lap: 58.93m
Case 2. Surface type: Grass, Topology: sloping, Distance per lap: 103.78m
Case 3. Surface type: Concrete, Topology: sloping, Distance per lap: 117.65m
Case 4. Surface type: Linoleum, Topology: Flat Distance per lap: 235.353m

Each case was performed twice, the first iteration was with just the battery to establish a base from which to compare the second iteration to, which utilized the Fuel Cell as an augmentation to the battery. During the iterations of each case, the initial voltage reading of the battery was noted. The researchers, then drove the buggy around each course, until the system voltage was at 7.70V or the next lap would take the voltage well below 7.70V. At the conclusion of each lap the system voltage and elapsed time were recorded. The problem I am dealing with is that each test started with a different initial voltage reading of the battery and I do not know how to compare the data because of it.