Not sure what sort of esc you are using,check the specs.If it says that the voltage range is up to 14.8v.that is 4S.Some brands auto detect the number of cells and set the Low voltage cutoff accordingly,some like my cc45,you have to program with the trans.Generally the 35 amp and above can handle more than 3S,but it pays to check beforehand.
Cheers,
Bleary.