Embraer EMB145 Operation Manual page 1707

ELECTRICAL AIRPLANE
OPERATIONS
MANUAL
BATTERIES
Two 24 V DC, 44 Ampere-hour, nickel-cadmium batteries supply
essential loads in case of an in-flight failure of all generators or if both
engines are shut down simultaneously and the APU is not available.
Both batteries can supply at least 40 minutes of power for essential
loads in an all-generator-failure condition.
During normal operation, Battery 1 is connected in parallel with
generators 1 and 3 (network 1). Battery 2 is connected in parallel with
generators 2 and 4 (network 2). Battery 2 also supplies power for APU
starting.
During APU starting, battery 1 is isolated from the load buses. While
battery 2 provides power for APU start, battery 1 provides stable
electrical power to the equipment that can be adversely affected by
voltage transients.
A selector switch on the overhead panel controls each battery. When
set to the AUTO position, battery contactors (BC 1 or BC 2) actuation
is controlled according to the Electrical Distribution Logic (EDL). When
the GPU is connected, the battery contactors open so that only the
GPU can supply the load buses. When on the ground, with the
batteries as the only electrical power source, EDL deenergizes the
shed buses for battery conservation. When the battery selector knob is
switched to the OFF position, the battery contactor opens, isolating the
battery from the system.
The batteries are installed in the battery compartment, on the left side
of the airplane nose section. They are ventilated in flight by forced
airflow to prevent overheating. Temperature sensors installed in each
battery provide temperature indication to the MFD. If battery internal
temperature rises above 70 C, a warning message is presented on the
EICAS. If a battery is isolated from the load buses, a caution message
is displayed on the EICAS.
In case of Loss of All Generators battery duration is 40 minutes,
considering three APU start attempts. However, be attentive to the
following condition: On ground, after starting the APU, batteries
voltage must be checked with all Generators disconnected. If
batteries voltage is below 24.0V, they must be recharged. The
minimum time for battery recharging is 30 minutes. Be aware that
while GPU is ON, batteries will not be recharged.
Page Code
2-05-05 6 01 REVISION 36