3.5 Flashcards
What is internal resistance?
The resistance inside a battery when connected to a load. It restricts the movement of current in any battery.
What does OCV and CCV stand for?
Open circuit voltage (OCV)
Closed circuit voltage (CCV)
For general purpose applications of batteries, what is important to remember about the IR?
It will not adversely affect and aircraft electrical system until the battery becomes over 75% discharged
What happens if the terminals of a battery are not clean?
The connections will not be very good increasing resistance and reducing voltage
How does a primary cell battery produce electricity?
Produce energy by chemical means
Non-rechargeable
What is a secondary cell battery?
A rechargeable battery used in aircraft, cars and laptops
What are types of secondary cells?
Lead acid or Nickel Cadmium
In a lead acid cell, in regards to the electrolyte, what is the percentage of sulphuric acid to water?
30% Sulphuric acid
70% Water
Nickel cadmium cells have a voltage of 1.2V. What does this fall to when discharged?
1V
What must you do to a nickel cadmium battery?
Refill the electrolyte.
Only done when fully charged as the level rises when charging
What are the advantages and disadvantages of using a nickel cadmium battery other than a lead acid battery?
Advantages
- better power to weight ratio
- CCV remains constant throughout discharge
- larger capacity
Disadvantages
- more costly
- larger
What type of battery set up should be used when a high voltage is required?
Cells connected in series
What type of battery set up should be used when a high current is required?
Cells connected in parallel
How is a lead acid battery charged?
The current is passed through the storage battery in the opposite direction
What is the IR of a battery determined by?
The load applied and the batteries state of charge
When does a batteries internal resistance rise?
As the battery discharges
What type of battery makes up a primary battery?
A zinc-carbon battery
Lead acid cells have a voltage of 2.0V. What does this fall to when discharged?
1.83V
Which type of voltage does a standard zinc carbon battery supply?
DC
In a primary cell battery which are the positive and negative electrodes? And what is the electrolyte paste?
The carbon bar is a positive electrode
Zinc forms the negative electrode
Manganese dioxide is the electrolyte paste (prevents hydrogen build up at positive electrode)
What does a lead acid cell consist of?
Positive plates filled with lead peroxide
Negative plates filled with spongy lead
Liquid electrolyte consisting of sulphuric acid and water
