It means the battery is not fully charged.
The emergency power supply consists of a charger, an inverter, a battery, an isolation transformer, a switching switch and other devices, which inverts direct current energy into alternating current energy.
When the industrial and civil buildings are in a state of fire emergency, in order to ensure the success of the fire rescue work, the independent power supply responsible for the power supply to the fire power equipment is called the emergency power supply.
\"Civil building Electrical Design Code\" clearly stipulates that the first load should be powered by two power supplies, when a power supply fails, the other power supply should not be damaged, the power supply of the first load has two high-voltage power supplies and one high-voltage power supply and one low-voltage power supply, diesel generator set or battery group.