The bistable cholesteric twist cell (BCTC) described here is a liquid‐crystal device which can be in either of two stable laminar configurations while a particular holding voltage is applied. The major shortcoming of previous implementations of this device was the narrow thickness tolerance required for proper bistable operation. In order to ascertain the effect which material parameters might have on increasing this thickness tolerance an adequate method is needed for characterizing the behavior of the cell. In this paper we describe a wedge cell method for characterizing the behavior of a given BCTC system. The characterization can be conveniently done within a single cell. The data obtained include both the thickness to pitch range for pratical bistable operation and the switching properties. All of these features can be interpreted in terms of static free energy curves calculated for the system. We have also used this wedge cell method to determine the effect of the bend to splay elastic constant ratio on the thickness range of bistable operation in the BCTC. The range is observed to increase with increasing ratio of bend to splay elastic constant. A material has been identified with a bistable thickness range in excess of 10%.