On the 1515 1/y, the 6s would be a tad on the hot side. 5s is warm, 4s is perfect.
i am aware, but thank you for the info. I plan on running on 4s and throwing in a 5s pack purely for vulgar displays of power.
I already have two 2s and a 3s for my Rusty. I can get 4s and 5s there with a series adapter. I will be buying separate batts for the revo though as I only have 1 battery tray.