摘要 |
A secondary battery is connected to a fuel cell, the fuel cell is disconnected from a load when the output of the fuel cell falls, and the load is activated with the secondary battery. When the remaining capacity of the secondary battery decreases and becomes less than or equal to a first level, an indicator for indicating running out of fuel is turned on to require refueling. When the remaining capacity becomes less than or equal to a second level, the load is disconnected even from the secondary battery.
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