Specifications

MARATHONNORCO AEROSPACE, INC.
NICKEL-CADMIUM AIRCRAFT BATTERIES
24-34-00
Page 1
APR 15/06
DESCRIPTION AND OPERATION
DESCRIPTION
General
The nickel-cadmium battery cell is an electrochemical system in which the active materials contained in the
plates undergo changes in oxidation state with very little change in electrolyte concentration due to the
production or consumption of water. These active materials are virtually insoluble in the alkaline (potassium
hydroxide) electrolyte in any oxidation state. As a result the electrodes are very long-lived.
Some of the electrochemical mechanisms involved in the charge, discharge, and storage of the nickel-cadmium
battery cell are rather complex. This is especially true of the positive plate. A brief simplified account of the
essential reactions is offered in order to help initiate the reader into the theory and principles of this system and
thus further the understanding of the operation of the battery and the role played by its main components.
GENERAL NICKEL-CADMIUM EQUATION,
chg.
2Ni(OH)
2
+ Cd(OH)
2
→ 2NiOOH + Cd + 2H
2
O
←
dischg.
Positive Negative Positive Negative
Plate Plate Plate Plate
FIGURE 1
Typical Constant Current Charge Curve
5-Hour Rate
1.2
1.3
1.4
1.5
1.6
1.7
1.8
0 1 2 3 4 5 6 7
CELL VOLTAGE
TIME/HOURS
TYPICAL CONSTANT CURRENT
CHARGE CURVE 5-HOUR RATE