AS113 - Lecture - Nickel-Cadmium Batteries

Question 1

Ni-Cad batteries require the user to completely use up their capacity before ________.

Answer 1

recharging

Question 2

______ _____ require higher current for starting.

Answer 2

Turbine Engines

Question 3

____ _____ has a tendency to build up sulfates on the plates when they are in use, which causes higher resistance and a voltage drop.

Answer 3

Lead acid

Question 4

_____ battery was developed for aircraft use because it has low internal resistance and voltage stays constant until the battery is discharged.

Answer 4

Ni-Cad

Question 5

Main disadvantages of a Ni-Cad Battery

Answer 5

Cell Imbalance (Battery Memory)

Heavy in weight

Potential for Thermal Runaway

Question 6

Nickel-Cadmium Battery Construction

Answer 6

Individual Removable Cells.

The cells are charged to an Open Circuit Voltage (OCV) of 1.55v to 1.80v.

12 volt system 9 or 10 cells 13.95v-18v.

24 volt system 19 or 20 cells 29.45v-36v.

Question 7

Positive Plates

Answer 7

Powdered nickel sintered (fused) to porous nickel mesh.

Porous mesh impregnated with nickel hydroxide.

Question 8

Negative plates

Answer 8

Powdered nickel sintered to porous nickel mesh.

Impregnated with cadmium hydroxide.

Question 9

Plates are separated with a _____ and _____ material.

Answer 9

nylon and cellophane

Question 10

Nickel-Cadmium Battery

______ is 30% by weight solution of potassium hydroxide and distilled water.

Answer 10

Electrolyte

Question 11

Nickel-Cadmium Battery

The electrolyte Specific Gravity is ____ to ____ @ room temperature.

Answer 11

1.240 to 1.300

Question 12

Chemical Changes During Discharge

Cadmium on ________ plates combine with hydroxide ions in electrolyte, which releases electrons.

Answer 12

negative

Question 13

Chemical Changes During Discharge

Hydroxide on _______ plates goes into the electrolyte solution.

Answer 13

positive

Question 14

Chemical Changes During Discharge

_____ ______ stays the same, so it does not give an indication of batteries state of charge.

Answer 14

Specific gravity

Question 15

Chemical Changes During Discharge

Electrolyte liquid level will be at its ______ when a battery is discharged.

Answer 15

lowest

Question 16

Chemical Changes during charge

The oxygen is driven from ________ plates.

This leaves the metallic cadmium on ________ plates.

This continues until all oxygen is released.

Answer 16

negative
negative

Question 17

During the charging cycle electrolyte is driven from the ______ and ______ plates.

Answer 17

positive and negative

Question 18

The liquid level of the electrolyte is at its ___ ____immediately after charging cycle.

This is the proper time to check the electrolyte level.

Check and add distilled water only when battery is fully charged.

Answer 18

highest level

Question 19

Servicing Ni-Cad Batteries

When cleaning tops of batteries.

Neutralize with ____ ____ or ______ and then flush with clean water.

insure that no neutralizing agents enter into the cells.

Answer 19

boric acid or vinegar

Question 20

A small accumulation of ______ ______ on top of the cells is common.

Answer 20

potassium carbonate

Question 21

______ is formed by the electrolyte combining with carbon dioxide.

Answer 21

potassium carbonate

Question 22

An excessive amount of potassium carbonate is caused by.

Answer 22

Battery was charged to fast.

Level of electrolyte too high.

Question 23

Internal short circuits.

Battery wont hold a ______.

Answer 23

charged

Question 24

Internal short circuits.

Check for electrical leakage between cells and steel case with ________.

_______ lead - terminal

_______ lead- case

Answer 24

ammeter
Positive
Negative

Question 25

When checking the internal short circuit with the ammeter it should not be no more than ____ mA

If its more than ____ mA disassemble and clean and retest .

Answer 25

100
100

Question 26

In Service Checks

Condition of cell hardware.

Should not have any ______.

Should be properly _______.

Answer 26

Corrosion
Torque

Question 27

Burn marks will result from improper ______ and ______.

Answer 27

torque and corrosion.

Question 28

Perform a measured discharge test to determine the ______ _______ of charge of NI-Cad battery

Answer 28

actual state

Question 29

To perform a measured discharge test.
Fully charge battery use a 5 hour rate (ampere-hours / 5 = charging amps)
adjust electrolyte when fully charged

Question 30

After performing a measured discharge

If capacity is normal recharged and _______ _______.

If capacity is not normal a
____ _____ may exist

Answer 30

return to service
cell imbalance

Question 31

Negative plates controls the cell’s voltage characteristics.

Lower charge efficiency in positive plate.

Answer 31

Cell Imbalance

Question 32

Imbalance between Negative and Positive plates.

Answer 32

Cell Imbalance

Question 33

Continue to discharge the battery but at a slower rate.

When cell voltage gets to .2vdc per cell, short the cells with shorting straps

Sometimes a load bank is used

Leave straps on 3 to 8 hours.

This will rid of cell imbalance

Answer 33

Deep Cycle or Equalization

Question 34

Charge per manufactures recommendations.

Monitor battery during charging cycle.

Looking for cell differential.

Nearing full charge- gases are released.

OCV is 1.55 to 1.80 volts per cell.

Answer 34

Deep Cycle Process

Question 35

High discharged rate and high charging rates

Answer 35

causes high temperature.

Question 36

_____ temperature breaks down the separator material (cellophane like material).

Answer 36

High

Question 37

______ circuit will occur if cellophane breaks down

allowing current flow to increase, causing more heat

Answer 37

Short

Question 38

More material break down, during thermal runaway causes

Answer 38

more current to flow.