Emergency Power Flashcards
What is the composition of a singular cell?
Contains two conductive electrodes (plates) of different material, and an electrolyte solution. The electrolyte reacts chemically with the electrodes, and acts as a medium for transferring electrons, creating potential difference between two electrodes.
What is open circuit voltage?
When no load is connected to the cell, the open circuit terminal voltage is equal to the voltage produced by that specific type of cell.
What is closed circuit voltage?
When current is drawn, there will be voltage drop across the cell due to internal resistance. The terminal voltage on the cell will be much less than emf.
What are the two fundamental types of batteries?
Primary, and Secondary
What is the most common type of primary cell?
Dry cell (doesn’t use liquid electrolyte. Uses powder)
- Chemical reaction during discharging destroys the electrodes, when battery is fully discharged the cell must be replaced.
- ex) one time use battery like a key fob battery or basic AA battery
What is another name for a secondary battery?
Storage cell or wet cell
What is the difference between a primary and secondary cell?
Primary cell (dry cell) cannot be recharged. Secondary cell (wet cell) can be recharged by passing current through the opposite direction of discharge.
What are the most common types of dry cells?
Carbon-zinc, zinc-chloride, alkaline, mercury, silver oxide, lithium.
What is the most common primary type battery?
lithium-manganese dioxide cell
What is the main practical use of secondary cells?
Used in emergency power systems because they are rechargeable
What voltage is a lead acid cell?
About 2.1V per cell
What is the most common primary cell?
Lithium-manganese dioxide cell
What is the open circuit voltage of a lithium cell (primary)?
3V, remains virtually constant throughout it’s operating life.
What are the main categories of secondary batteries?
SLI - engine starting, lighting, and ignition
Motive power - for electric vehicles
Standby batteries - for emergency power equipment and alarms
Portable batteries - for tools and equipment
What are the two long-life storage battery types?
Lead-acid, nickel-cadmium
What is an advantage of the primary lithium cell battery?
Can operate at a wide range of temperatures (-20 - +55), has a constant voltage of 3V
What are the main categories of secondary batteries?
- SLI (for engine starting, lighting, and ignition)
- motive power for electric vehicles
- standby for emergency power equipment and alarms
- portable for tools and equipment
What are the two types of long-life storage batteries?
lead-acid, nickel-cadmium
What is the general makeup of a lead acid battery?
positive-plate electrodes of lead dioxide, negative-plate electrodes of sponge lead, supported within lead alloy grid structure. Electrolyte is sulphuric acid and water.
What is a hydrometer?
A tool that measures the density of the electrolyte, shows the condition of the battery
How does a hydrometer work?
The float will rise with an increase in relative density or charge. Float will indicate red, white, or green.
Red is poor condition or completely discharged.
White needs charging
Green is good condition, and charged.
What are the full charge amounts for stationary batteries?
Full charge: between 1210-1225
Fully discharged: between 1180 and 1195
What are the full charge amounts for portable batteries?
Full charge: between 1280 - 1300
Fully discharged: between 1100 - 1130
What types of batteries are sealed/maintenance free?
Absorbed Glass Mat (AGM), and Gel type.