a 10 b and the ring 15 the ring 15 has rectangular shape complementary to the outer edge of the switch assembly 12 and opposing planar faces 17 a 17 b the ring 15 is formed of a substantially rigid polymer a neck 16 of the switch assembly 12 includes electrical conductors not shown and extends through a channel not shown in the ring 15 to connect to the pcb 6 the rigid tubular outer cover 18 is elongated parallel to a longitudinal axis of the cell containers 5 a 5 b and conforms tightly to the outer surfaces 10 a 11 b to clamp the ring 15 between the surfaces 10 b and 11 a the pcb 6 lies generally perpendicular to the parallel planes of the cell containers 5 a 5 b and adjacent to a transverse edge 19 to provide a compact package that nests within the casing halves 2 3 referring to fig5 and 6 the sealed battery cell containers 5 a 5 b each hold a positive and negative electrode 30 31 and an electrolyte 32 the membrane switch assembly 12 is of a type comprising three normally open switch elements 13 a 13 b 13 c electrically connected in parallel as used herein the term u201c membrane switch u201d refers to a pressure sensitive momentary switch in which at least one electrical contact is on or made of a thin flexible substrate each of the switch elements 13 a 13 b 13 c includes thin flexible substrates 20 21 each carrying a respective pole 22 23 held apart by resilient action of the dome shaped substrate 20 the substrate 21 abuts the surface 11 a of cell container 5 a and substrate 20 is spaced apart from.