Okay the name helped. I went out to the CC site (by the way their tech people are very friendly and helpful) and looked at the TB54 esc. The label shows "12c/3sl" which is simply CC's shorthand for "12 nickelXX cells or 3 LiPos in series. No mystery, but a poor choice of terminology as per your confusion. This label entry has nothing to do with battery output, only the maximum number of cells of a particular type that can be used - note maximum, not minimum number of cells.

Glad to help,
Walt