214-A Exam 2

Module 3-5

Positive plate of a lead acid battery is made out of?

Lead peroxide

An OCV of a lead acid battery is called?

2.10 VAC

A.Primary Cell

B.Secondary Cell

A. Can be used once

B. Rechargeable

How can you tell when a
(NiCAD or Lead Acid)
battery on constant
current charge is fully
charged?

Battery voltage stops rising.

Low internal resistance in
a NiCAD can cause

Thermal Runaway

If a battery has a 45 AH
rating, how long can it
supply 9 amps?

5 Hours

The correct sequence for
turning on aircraft power
to test a radio is

GPU, Avionics Master, then Radios.

Typical inputs of a GPU

120 VAC

220 VAC

340 VAC

What are the active materials in a nickel-cadmium cell? (Ni-Cad)

(Ni (OH)2) (Cd (OH)2) - (NiOOH)

What are the active materials in a lead-acid storage cell?

Spongy lead (Pb) sulfuric acid (H2SO4)

What electrolyte is used in a lead-acid storage cell?

H2SO4 sulfuric Acid

What determines the voltage of an aircraft storage battery?

Number of cells that are connected in series & voltage of each individual cell.

What ratings are used to describe aircraft storage batteries?

Voltage and ampere-hour capacity. Additional ratings may include discharge rate, operating temperature

safety precaution when working with lead-acid storage batteries.

Have PPE, charge in a well-ventilated area, remove from aircraft if charging, and

remove negative first & reconnect it last.

Explain the difference between constant-voltage charging and constant- current charging.

Constant volt- Fixed volts and current decrease while charging

Constant current- Fixed current remains & voltages increases

What type of charging is employed in an aircraft electric system?

Constant Voltage & current

What is the danger caused by loose cell connectors in a nickel-cadmium battery?

High resistance, overheating, cell imbalance, sparking, and potential fire

How would you adjust the specific gravity for a lead-acid battery?

Adding distilled water or adding electrolyte to raise it

What are the two voltages used for an aircraft batteries?

14 V

24 V

What is the purpose of an aircraft battery

Start the aircraft or APU

Source of power when the generators are unavailable 

What is Lead acid composed of?

Secondary cells with lead compound plates in sulfuric acid & distilled water.

How many volts does a Lead-acid have?

2.1V

What is the battery construction for Lead- acid battery have?

Contains 6 or 12 Volts

Each cell produces 2.1V

PbO2 & Pb & H2S04

Explain the lead acid battery

Upright- Normal position

Upside down- Stops the electrons spilling out

Chemical reaction Lead Acid

Lead(Pb) at the negative plate & lead dioxide (PbO₂) is at positive and they react with sulfuric acid (H₂SO₄) to create lead sulfate (PbSO₄) and water (H₂O) creates 

Load testing for Lead acid

Open circuit voltage and closed circuit voltage may be compared with the aid of a battery load tester

What is Ni-Cads cell voltage

1.25 V

Explain the chemical reaction which makes

the nickel-cadmium battery a voltage source.

Nikel Hydroxide travels KOH & Cd to CdOH & NiOOH

Explain reason of thermal runaway?

It is caused by breakdowns of insulating cell due to excessive heat or overcharging

Procedures to prevent thermal runaway?

Have temperature monitoring system & battery should be disconnected from electrical.

Safety Maintaining Ni-Cad Batteries

safety Glasses

remove jewelry

use proper lifting techniques

wear coveralls

secure in a ventilated are

Maintaining Ni-cad & lead Acid

Ni-Cad batteries and Lead Acid batteries should not be I the same room.

Due to fumes given off by each battery will neutralize the other or short circuit

Ni-Cad Batteries Maintain Records

• Good records show how the battery and aircraft are performing.

• If a Ni-Cad needs lots of water, flights are short — service it more often.

• Long flights keep the battery fully charged, use less water, and need less servicing.

What to do if there is a spillage of Lead Acid

Baking Soda & water

What to do if there’s a spillage of Nicad

Weak acid, vinegar 

Installation of Lead Acid

Often with sump jar in an exhaust vents and neutralize vented acid fumes to protect airframe. Manifold type, where batteries are vented through a shared manifold or tube system.

Describe the output voltage requirements for D.C. power carts

14 VDC

28 VDC

115 VAC, 400 Hz

Constant current vs constant voltage charging

which is used in aircraft

Constant voltage

Constant current vs constant voltage charging

which is used in a shop

constant current

Indications of nearing full charge

Current will start to decrease and Voltage will stop increasing

POWER UP procedure

Power down Procedure

safely apply D.C. ground

power to an aircraft.

1) Position of the landing gear handle.

2) Position of the flap selector switch.

3) Circuit breakers set.

4) Switches off.

5) Avionics master switch off.

6) Radios turned off.