3.5 Dc Flashcards
Definition and characteristics of primary cells
Supply voltage immediately without prior changing
Electrochemical processes are not reversible
Cannot be recharged or reused but can be recycled
Galvanic cells ?
Supply a certain current over time with capacity depending on construction and size
Nearly all primary cells are dry cells with paste electrolytes
Definition and characteristics for zinc carbon dry cells
Zinc container serves as a negative electrode
Positive electrode is a central carbon rod
Contains a paste of manganese oxide, zinc chloride, carbon powder
Initial voltage is about 1.5v which decreases over time
Large batteries store more energy
Prone to leakage due to zinc containers oxidation
Alkaline primary battery
Improved over zinc carbon with 5 times more energy
Also prone to leakage
Can be recharged but with limited Recharge cycle
Not expensive but less durable
What type of reactions occur in secondary (rechargeable) cells, and how can they be restored?
The electrochemical reactions in secondary cells are reversible, and the chemical reactants can be restored (recharged) by running a charging current into the cell.
What materials are typically used to make secondary cells in aircraft storage batteries?
Secondary cells in aircraft storage batteries are typically made of lead acid or nickel cadmium.
What materials are typically used to make secondary cells in aircraft storage batteries?
Secondary cells in aircraft storage batteries are typically made of lead acid or nickel cadmium.
How are the cells in aircraft storage batteries connected, and what is this configuration called?
The cells in aircraft storage batteries are connected in series, and this configuration is called a “battery of cells” or simply ‘battery’.
How much voltage does lead acid cells have ?
2.2 v which would fall to 1.8v when discharged
How much voltage does nickel cadmium have?
1.2 v fall to 1 v when discharged
Comparison of nickle cadmium to lead acid battery state the advantages
Tolerates higher discharge currents
Closed circuit voltage remain almost constant throughout discharge
Higher energy density
Greater number of charge/discharge cycles
Comparison of nickle cadmium to lead acid battery state the disadvantages
More costly
More complicated charging requirements
Rish of thermal runaway as the battery tempt rises the internal resistance decreases
High toxicity of cadmium
When would you use thermocouples
To measure high temperatures and or in hard to reach places
What does voltage depends on
Light intensity
