Flashcards
3. Batteries
Cards in this deck (56)
- 1define Primary Cellsbatteries comprising of primary cells are not rechargable
- 2define secondary cellsbatteries compromising of secondary cells are rechargable
- 3what is the use of primary cellsemergency lighting
- 4what is the general use of secondary cells in batteriesthey are the main type used in aircraft
- 5what is the positive plate in a lead acid batterylead peroxide
- 6what is the negative pate in a lead acid batteryspongy lead
- 7what is the electrolyte of a lead acid batteryDistilled water and sulphuric acid
- 8what is the charge on a fully charged lead acid battery2.2 volts
- 9what is the voltage on a fully discharged lead acid battery1.8 volts
- 10how many cells will you usually find in an aircraft lead acid batteryeither 6 or 12 cells
- 11in what way are cells in batteries connectedin series
- 12when is the lead acid battery considered to be dischargedwhen spg has fallen from 1.27 to 1.1 SG
- 13Which will freeze first, the electrolyte when fully discharged or fully chargedwill freeze first at a fully discharged level
- 14how can you recharge lead acid batteriesconnecting positive and negative terminals respectively to the terminals to a DC source of a slightly higher voltage
- 15what happens when a battery is rechargedthe reduction and oxidation reactions are reversed
- 16why are alkaline batteries preferred to lead acid batteriesmore stable voltage during discharging
- 17what is the positive plate of the NiCd batterynickel oxide
- 18what is the negative plate of the NiCd batterycadmium
- 19what is the electrolyte used in NiCd batterypotassium hydroxide
- 20what is the voltage when fully charged1.2 volts
- 21what is the voltage when fully discharged1.1 volts
- 22how many cells would be in a typical NiCd battery20 or 22 cells
- 23what is the SP of the electrolyte when charged1.26 SG
- 24does the SG change when it dischargesno
- 25what is a major disadvantage of the nickel Cadmium batteryit suffers from the memory effect
- 26define the memory effectwhen the battery is not fully discharged and then the cadmium crystals build up on the plates. next time it is discharged the cadmium crystals lower the SA available and therefore the battery can no longer be discharged below this point
- 27what happens when charging a batterythe temperature increases and hydrogen is given off
- 28due to the evaporation of the distilled water in the electrolyte what has to be done to the batteryit has to be refilled with distilled water
- 29what are the two methods of venting associated with lead acid batteriesnon-spill vents
cell cross flow vents - 30define the non spill vent systemallows the hydrogen gas to escape while retaining the electrolyte
- 31define the cell cross flow systemcabin pressurisation air flows over the across the cells to vent the batteries
- 32what are the two ways to vent a alkaline batterysemi open batteries
sealed batteries - 33define semi open batteriescells are allowed to gas freely to avoid overheating, safely vented to the atmosphere
- 34define sealed batteriescells are completely sealed and require no maintenance
- 35what is the neutralising agent used in a lead acid battery electrolyte spillagebicarbonate of soda
- 36what is the neutralising agent used in a alkaline battery electrolyte spillageboric acid
- 37define capacitymeasure of the total amount of energy it contains
- 38what is capacity measured inAmpere hours
- 39what is Capacity dependant onsize
number of plates - 40what does a batteries actual capacity have to be80 % of manufactures indication
- 41how often does a batteries capacity have to be checkedevery 3 months
- 42what are the two methods of battery charging in an aircraftconstant voltage
pulse charging - 43define pule chargingdc pulse charging happens to keep the battery topped up
pulses of DC - 44define constant voltageaircraft using a 12 volts battery, the generator is selected at 14 volts
- 45in constant voltage charging what is the charging rate proportional tothe difference between the battery and the generator voltage
- 46what would happen if the voltage supplied to a lead acid battery is too highthe plates may distort
- 47define thermal runawaywhen the temperature conditions are exceeded, and the internal resistance drops, allowing a higher current to flow.
- 48what can thermal runway causeboiling of the electrolyte, violent gassing and explosion of the battery
- 49how can you find the state of charge of a lead acid batterymeasuring the terminal voltage
measuring specific gravity - 50what is the effect of temperature on battery capacityhuge effect, some batteries have thermal blankets wrapped around them to keep them at an optimum temperature during flight
- 51what does the pre-flight check of the batteries involve-check off load voltage when offload
-check stipulated load voltage
-compare and ensure it is within a set tolerance - 52according to CS25 how long must the main batteries be operative for after total failure of generating system30 minutes
- 53according to CS25 how long must the emergency lighting batteries be operative for after total failure of generating system10 minutes
- 54when in series what can you say about the voltage and capacity of the entire circuitvoltage added
capacity the same - 55when in parallel what can you say about the voltage and capacity of the entire circuitvoltage same
capacity added - 56what is important to note about connecting batteriesacid and alkaline batteries must never be mixed
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- AGK (Electrics) Flashcards on 3. Batteries, created by Ella Davies on 27/03/2018.
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