Each cell of a fuel cell stack is provided, between the anode 37 and
cathodes 38, with either (a) a permanent shunt (20) which may be
a discrete resistor (42-44), a diode (95), a strip of compliant carbon
cloth (65), or a small amount of conductive carbon black (22) in
the ionomer polymer mixture of which the proton exchange membrane (39) is
formed, or (b) a removeable shunt such as a conductor (69) which may be
rotated into and out of contact with the fuel cell anodes and cathodes, or a conductor
(85) which may be urged into contact by means of a shape memory alloy actuator
spring (90, 91), which may be heated.
