Historic Size of Battery

[MrForbes]

Another thing you could do is to get all the design work done, then hold off on building the car until after kickoff, when you know for sure what the batteries will be.

Or if you're into assumptions, you could read the list of rookie/veteran parts variables

http://usfirst.org/uploadedFiles/Com...write%20up.pdf

and assume that since veteran teams are not getting as many batteries as rookie teams, that the same batteries will be used next year. But note that it also says that battery rules are under review.