Fuel cell system water management strategy for freeze capability

A fuel cell system for a vehicle, said system comprising:

• a fuel cell stack including reactant gas flow channels;
• a compressor for forcing air through the reactant gas flow channels;
• a controller configured to control the fuel cell system, said controller determining whether a potential freeze condition exists at fuel cell system shut-down based on predetermined parameters, said controller causing the compressor to purge the reactant gas flow channels if the potential freeze condition does exist, said controller shutting the fuel cell system down normally without a reactive gas flow channel purge if the potential for a freeze condition does not exist, said controller periodically determining after the normal shut-down whether a potential freeze condition exists, and said controller performing the reactant gas flow channel purge if the subsequent determination of a potential freeze condition exists, said controller initiating a keep warm strategy if the controller determines that the potential freeze condition exists after system shut-down before performing the purge, wherein the controller determines whether there is enough fuel or battery energy to perform the keep warm strategy based on predetermined criteria, and if not, perform the purge;
• and
• a wake-up circuit for waking up the controller to perform the purge after system shut-down.