Milwaukee cordless drill batteries (2 of em) - the charging stations in the pits were a sight to see. (FIRST took care of charging the batteries, meaning there was a very long table with hundreds of red Milwaukee chargers all in a row).
This was one of the years when FIRST was responsible for charging batteries for all the teams. I think they ended up with a huge backlog, leaving certain teams without batteries for matches.
The contraversy was over those silly Grey tabbed batteries. Some teams were using them instead of the black tabbed batteries…it was found that the Grey tabbed batteries had more of an advantage to them.