A power supply system 10 with a stack of fuel cells 20 and a storage battery 30 includes a remaining charge monitor 46 for measuring the remaining charge of the storage battery 30. The remaining charge monitor 46 detects the remaining charge of the storage battery 30 at the time of stopping operation...http://www.google.co.uk/patents/US6158537?utm_source=gb-gplus-sharePatent US6158537 - Power supply system, electric vehicle with power supply system mounted thereon, and method of charging storage battery included in power supply system
