3.5 Flashcards
In aircraft storage batteries, secondary cells are made form?
Lead acid and nickel cadmium
Connected in series
If you want higher voltage what way would you connect the batteries
In series
A lead acid cell consist of what
Positive Plates (lead peroxide) Negative Plates ( pure spongy lead) Liquid electrolyte (sulphuric acid(30%) and water(70%))
What does CCV stand for?
Closed circuit voltage
The resistance inside a battery connected to a load is called?
Internal Resistance (IR)
What makes up nickel cadmium cells?
Positive plate(nickel oxyhydroxides) Negative plate (metallic cadmium) The electrolyte (potassium hydroxide)
What does IR do?
Restricts the movement of current inside any battery
What does OCV stand for?
Open circuit voltage
What type of cells are rechargeable
Secondary
What voltage does nickel cadmium have when discharged
1V
During discharge of secondary cells, what happens to the sulphuric acid
Breaks up into hydrogen ion (positive) and sulphate ion (negative)
What are the disadvantage of nickel cadmium over lead acid
Costly
Larger
During discharge, what happens to the negative plate?
It deteriorates and goes into the solution
How long will it take until the IR of a battery will not affect the aircraft electrical system
Until it becomes over 75% discharge
Lead acid cells has what voltage when charged
2V
When is it said that a battery of lead acid is discharged?
When both plates are coated with lead sulphate and no further chemical action can take place
For higher current, what way would you connect a battery
In parallel
What happens when the battery discharges
The batteries internal resistance increases
What voltage does lead batteries have when discharged
1.83V
What is used to prevent the build up of hydrogen at the positive electrode of the cell?
Manganese Dioxide paste
In a zinc carbon battery what is positive and what is negative
Zinc= negative electrode
Carbon =positive electrode
Zinc carbon batteries provide what type of voltage
Low voltage dc supply.
What is the electrolyte level when the nickel cadmium cells is discharged?
At its lowest
What are the advantages do nickel cadmium over lead acid
Better power to weight ratio
Closed circuit voltage
Larger capacity
If the terminals are not clean,what will happen to the connection
It will not be very good
What happens when you recharge up lead acid
The sulphate ions are driven back into the solution and combine with hydrogen to create sulphuric acid and the plates return to its original composition
Nickel cadmium has what voltage
1.2V
What is an primary cell and an example of one?
Are batteries you can by in shops
E.g Zinc Carbon battery
