BATTERIES - MAIN AND APU BATTERIES
Purpose
When ac power is not available, the main battery does these functions:
Supplies power to dc loads that are necessary for ground operation
Supplies power to all the components that deploy the RAT
Supplies standby system power until the RAT generator starts to supply power.
The main battery can supply standby system power for at least five minutes.
The APU battery supplies electrical power to start the APU.
Physical Description
The main battery and the APU batteries are rechargeable. They are fiber nickel-cadmium (FNC) batteries. Each battery weighs 106 lb (48 kg).
Each battery has two sets of ten FNC cells. The battery case is green. The case has two mounting flanges and two lifting handles. Bolts attach the mounting flanges to the airplane. The lifting handles help you connect ground support equipment (GSE) to the battery when you move it.
The battery has a terminal block and an electrical connector. The terminal block connects the high power output. The electrical connector connects control and status signals.
The battery has a temperature sensor and an overheat switch (not shown).
The battery has both ambient and battery temperature sensors, and an overheat switch (not shown). The battery cooling fan comes on when the battery gets hot.
Training Information Point
WARNING:
BE CAREFUL WHEN YOU MOVE THE BATTERY. BECAUSE THE BATTERY WEIGHS 106 POUNDS (48 KG), INJURY TO PERSONS CAN OCCUR.
Use ground support equipment to lift the main battery. You install a rack and pulley between the floor beams above the battery to help you lift it.
The APU battery attaches to a tray that you can pull out to easily remove and install the battery. When you push the tray in, there are two captive screws you must tighten to prevent tray movement.
CAUTION:
DO NOT CHARGE THIS BATTERY WITH BATTERY CHARGERS WHICH ARE NOT APPROVED FOR THIS TYPE OF FNC BATTERY. OVER-CHARGING CAN OCCUR AND SERIOUSLY DAMAGE OR DESTROY BATTERY CELLS.
The capacity of each battery is 47 amp-hours. The main battery can supply the hot battery bus loads for 10 days.
The main battery and the APU battery are interchangeable.
No maintenance is necessary for FNC batteries.
When no other power is on the airplane, the hot battery bus supplies power to the static random access memory (SRAM) of the AIMS. If you disconnect the main battery with no power to the AIMS cabinets, you lose some data. See the AIMS section for more information