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 Two dissimilar metals in an electrolyte  Electrolyte can be  Also known as a voltaic cell  Only able to be used once Primary Cells Revision Alkali (Base) Acid Salt Can’t be recharged

Primary Cells Revision Dependant on electrode type Dependant surface area of electrode  Cell Voltage:  Cell Current:  Suffers from: “Local Action” “Polarisation”

 Plates generally are of the same material  Electrolyte is:  Chemical reaction is reversible Secondary Cells Acid Alkali (Base)

Plante Cell Developed by Raymond Gaston Plante

Lead (Pb)Lead (Pb) Sulphuric Acid (H 2 SO 4 )

ChargedDischarged Pb + HSO H 2 O Anode Cathode PbO 2 + 3H 3 O + + HSO e - PbSO 4 + H 3 O + + 2e - PbSO 4 + 5H 2 O Lead Sulphuric Acid Water Lead Peroxide Lead Sulphate AcidNo Acid Cell Voltage = 2V

Charged ∙A∙Anode or Negative plate Lead ∙C∙Cathode or Positive plate Lead peroxide (Brown) ∙A∙Acid as electrolyte Discharged ∙B∙Both Negative & Positive plates Lead Sulphate ∙W∙Water as electrolyte

LLead is soft, plates distorted easily AAmps/m 2 small, surface area needed to be increased (post card size only produces 1 Amp) PPlates change size as they take on sulphate CCannot remain uncharged as Sulphate crystals grow (can’t be converted back)

Developed by Camille Alphonse Faure ( ) 1880 coated lead plates with a paste of lead oxides, sulphuric acid and water, which was then cured. The curing process caused the paste to change to a mixture of lead sulphates 1881 Plates were perforated to provide a key for paste and to increase surface area Red lead Pb3O 4

Cast perforated lead plate Pasted lead plate Separator

Additives alloyed with lead to increase strength may include: Antimony Tin Calcium Selenium Plates are made thin and stacked to increase current output Number of plates indicate cells output

Designed to provide high currents for short periods of time :- CC (Cranking Current) Discharge Typical = 5-10% of capacity Maximum = 20% of capacity Standard Automotive Batteries

Designed to provide Low currents for long periods of time Discharge Maximum = 80% of capacity Deep Cycle battery Plates are thicker & may be solid construction

Designed to start motors and provide some low currents for periods of time Discharge Maximum = 50% of capacity Standard Automotive Batteries Deep Cycle battery Plates standard construction but are thicker Hybrid, or Marine battery

Standard Automotive Batteries Deep Cycle battery Hybrid, or Marine battery Maintenance Free or VRLA battery

Valve Regulated Lead Acid Absorbent glass mat (AGM) Gel Cell Chemical reaction causes release of: Hydrogen Oxygen

 Replacement of Antimony  Increasing the capacity of the negative plate Calcium Selenium Tin Negative plate gives off Hydrogen when fully charged If area of –ve plate is larger than +ve plate it will never reach full charge.

electrolyte is absorbed into a mat of fine glass fibres like wet cell lead acid battery in a rectangular case wound plates are thin lead in their plates are purer as they no longer need to support their own weight internal resistance is lower than traditional cells due to close plate proximity and the pure lead plates have lower resistivity Flat Cylindrical/Spiral

Sulfuric acid is mixed with a silica fume, which makes the resulting mass gel-like and immobile Do not need to be kept upright (though they cannot be charged inverted). Virtually eliminate the electrolyte evaporation, spillage (and subsequent corrosion issues) common to the wet-cell battery Often referred to as sealed lead-acid (SLA) batteries Antimony in the lead plates is replaced by calcium often referred to as a lead-calcium battery

Negative / Anode: Positive / Cathode:Nickel oxide-hydroxide Iron Electrolyte:Potassium hydroxide Cell Voltage:1.2 Volts

Invented by: Waldemar Jungner 1899 Developed by: Thomas Edison 1901 Also invented the Nickel-Cadmium battery 11903 to 1972 by the Edison Battery Storage Company 11972 the battery company was sold to the Exide Battery Corporation which discontinued making the battery in 1975 OOnly manufactured in china as of 2008

Advantages Very long life ≈ 20Years Tolerant of abuse Plates do not corrode like Lead Acid Can be left discharged Does not contain dangerous chemicals Overcharge over-discharge short-circuiting thermal shock Disadvantages Low energy to weight ratio Slow to take/ deliver charge More expensive than lead acid

1.-1 hr discharge rate 2.-2 hr discharge rate 3.-3 hr discharge rate 4.-4 hr discharge rate 5.-8 hr discharge rate hr discharge rate hr discharge rate 8. Normal charge 9. Rapid charge

Problem where the Ni-Cd battery would remember the amount of discharge for previous discharges and limit the recharge life of the battery Memory effect Crystal growth can occur when a modern Ni-Cd battery is recharged before it is fully discharged. The crystal growth can eventually prevent the battery from discharging beyond that point and/or cause rapid self-discharge of the battery Satellite technology

 Series  Parallel  Series/Parallel Higher voltage than a single cell can supply Higher current than a single cell can supply Higher voltage & current than a single cell can supply

2 Volt 0.5 A 2Total Voltage =46 Total Current = 0.5 A

2 Volt 0.5 A Total Voltage =2 Total Current =

 Materials used in the cell  Surface area of the electrodes  Distance between the electrodes  Operating temperature of the cell  Cells state of charge Dependant upon: Look at this next lesson

LLimit in the maximum current that can be supplied by the cell TTerminal voltage drops as current increases Causes a:

2V 0.2  2/0.2 =10 Amps RiRi 2.0  2/2 =1 Amp 20  2/20 =0.1 Amp Maximum Current

2V 0.2  2-(0.2 x 0.1) =1.98 Volts RiRi 2.0  2-(2 x 0.1) = 1.8 Volts 20  2-(20 x 0.1) = 0 Volts Terminal Voltage Load Current = 0.1 Amp

Parallel connected Cells RiRi Ri = 0.1  R i = 0.1  0.05   R i =  V = 2 V Number of cells

Series/Parallel connected Cells R i x Number of series cells in branch R i = R i = 0.15  V = 6 V Number of Branches Ri = 0.3  0.3  

 CCA  CA measurement of the number of amps a battery can deliver at -17° C for 30 seconds and not drop below 7.2 volts Cold Cranking Amps measured at 0° C. This rating is also called Marine Cranking Amps. Cranking Amps Hot Cranking Amps is seldom used any longer but is measured at 26.7°C

 CCA  CA  RC  AH Cold Cranking Amps Cranking Amps the number of minutes a fully charged battery at 26.7° C will discharge 25 amps until the battery drops below 10.5 volts. Reserve Capacity If a battery is rated at 100 amp hours it should deliver 5 amps for 20 hours Amp Hour

Standard lengths of time are 10 or 20 Hours 100Ah battery should supply:1 Amp for 100 Hours 2 Amps for 50 Hours 5 Amps for 20 Hours 10 Amps for 10 Hours 10 hours for standard batteries 20 hours for deep cycle batteries 100 Amps for 1 Hour Not possible as battery may not be able to deliver this current Decreasing the discharge period decreases the AH output of the battery

Battery Charging

Cell Charging AAppling a voltage that is larger than the cells terminal voltage CCurrent then flows in the opposite direction CChemical change takes place EEnergy is stored as a chemical change

 Materials used in the cell  Surface area of the electrodes  Distance between the electrodes  Operating temperature of the cell  Cells state of charge Dependant upon:

Increases as cell discharges Decreases as cell charges

 CCA  CA  RC  AH Cold Cranking Amps Cranking Amps Reserve Capacity Amp Hour

 Measurement of open circuit terminal voltage  Measuring the acid concentration  Placing the battery under a controlled load  Coulomb counting  Electrochemical Impedance Spectroscopy

 Cell Type  Cell temperature  Cell age  Time since last charge Factors to consider:

Electrolyte Temperature (Celsius) 100% SoC 75% SoC 50% SoC 25% SoC 0% SoC 48.9° ° ° ° ° ° ° ° ° ° ° ° ° Lead Acid

Electrolyte Temperature (Celsius) 100% SoC 75% SoC 65% SoC 50% SoC 25% SoC 0% SoC 48.9° ° ° ° ° ° ° ° ° ° ° ° ° Lead Acid (Ca)

ratio of the density of a given solid or liquid substance to the density of water at a specific temperature and pressure. Acid Concentration Measurement Specific Gravity Generally at 4°C and 1 atmosphere Battery Standard = 30° C Can’t be measured on Alkaline cells

Electrolyte Temperature (Celsius) 100% SoC 75% SoC 50% SoC 25% SoC 0% SoC 48.9° ° ° ° ° ° ° ° ° ° ° ° °

33 x of batteries AH rating is placed across terminals AAfter seconds terminal voltage is measured TThe higher the voltage the better the battery VVoltage should not be less than 9.6V OR ½ x CCA of Battery 1.6 V

CCoulomb = Current and Time CComputerised CCurrent is measured going into and out of the battery

IInjects Multiple frequencies ranging from 20- 2,000 Hertz. TThe signals are regulated to very low voltages TThe results are computer analysed to determine batteries capacity Electrochemical Impedance Spectroscopy

Cell Charging  Appling a voltage that is larger than the cells terminal voltage  Current then flows in the opposite direction  Chemical change takes place  Energy is stored as a chemical change Compromise between Plate (Grid) Corrosion or Sulfation High VoltageLow Voltage 2.45 V2.30 V

Type dependant on how the battery is used Permanently Connected Isolated to be charged

Float Output Voltage lower than normal charges to reduce danger of over charging Output Current supplied at very low levels, but above leakage currents

Lead Acid

Lead Acid (Ca)

Lead Acid (AGM)

Lead Acid (Gel)