Not sure if the relationship is really so linear, but you could try using a ratio of WH/m. Say your truck has a mass of 4000g. Lets also say that you KNOW that your truck will run for 20 minutes on a 2500WH pack. Now with the heavier pack (~700g) added (~4700g total) you would need a pack that stores ~2940WH.
Since: 4700g/4000g=1.175 and so 1.175*2500WH=~2940WH
Of course there are other things to consider. But assuming your driving style is constant through every lap (
) then all that we are playing with is inertia. So the extra WH should fill in the gap where the extra power is needed to accelerate the heavier vehicle and achieve the same run time. This also assumes that the power system draws the same power at the higher voltage, etcetera, etcetera....
Any pack within your weight limit with a
higher WH than the ~2940 figure
should in theory give longer run times.
I hope this made sense. It's almost 4 in the morning so I can't tell....
