General - AM.I.A.K15 - Aircraft batteries Flashcards
What is meant by the capacity rating of a lead acid battery?
The number of hours a battery can supply a given current flow
What electrolyte is used in a lead acid battery?
A mixture of sulfuric acid and water
Does the specific gravity of the electrolyte in a lead acid battery increase or decrease as the battery becomes discharged?
It decreases
What is the specific gravity of a fully charged lead acid battery?
Between 1.275 and 1.300
How many cells are there in a 24 volt lead acid battery?
12
What is the range of temperatures of the electrolyte in a lead acid battery that does not require a correction when measuring its specific gravity?
Between 70 and 90 degrees Fahrenheit
How do you treat a lead acid battery compartment to protect it from corrosion?
Paint it with an asphaltic (tar-based) paint or with a polyurethane enamel
What is used to neutralise spilled electrolyte from a lead acid battery?
A solution of bicarbonate of soda and water
How high should the electrolyte level be in a properly serivced lead acid battery?
Only up to the level of the indicator on the cell
Why is the closed circuit voltage of a lead acid battery lower than its open circuit voltage?
Voltage is dropped across the internal resistance of the battery
What gases are released when a lead acid battery is being charged?
Hydrogen and oxygen
What is the electrolyte used in a nickel cadmium battery?
Potassium hydroxide and water
What is a hydrometer not used to measure the state of charge of a nickel cadmium battery?
The electrolyte of a nickel-cadmium battery does not enter into the chemical changes that occur when the battery is charged or discharged. Its specific gravity does not change appreciably
Is the electrolyte level of a nickel cadmium battery lowest when the battery is fully charged or fully discharged?
Fully discharged
What is the result of cell imbalance in a nickel-cadmium battery?
The low internal resistance allows current to flow between the unbalanced cells and generate heat
What is a thermal runaway?
The large current flow allowed by the low internal resistance causes the cells to produce more heat than than they can dissipate. The heat further lowers the internal resistance so more current can flow. This continues until the battery destroys itself
How may thermal runaway be prevented?
By carefully monitoring the temperature of the cells and controlling the charging current to prevent and excess of current flowing into the battery
How is it possible to know when a nickel cadmium battery is fully charged?
Completely discharge the battery and give it a constant current charge to 140% of its ampere hour capacity
What is used to neutralise spilled electrolyte from a nickel cadmium battery?
A solution of boric acid and water
