State the purpose of a battery.

Batteries are used to provide power for auxiliary and emergency requirements. Larger stationary batteries are typically mounted on racks and maintained in a state of full charge, except for occasional discharges, to support electrical system functions.

Define Cell

Define Battery

Chemical action dissolves one of the electrodes. When cell is discharged, it is normally discarded or recycled. (AA or AAA battery)

Measure of battery capacity.  Fully charged lead-acid batteries are rated by amount of discharge current continuously supplied for a specific length of time. Usually expressed in ampere-hours (Ah).

Define Specific gravity

Ratio of the weight of sulfuric acid to the weight of an equal volume of water at a specified temperature.  It is used as an indicator of the state of charge of a battery. Ratio comparing density of a substance (electrolyte) to the density of water.

Hard rubber or plastic case used to contain the electrodes and electrolyte.

Space below cell plates is allowed for collection of sediment. 

Space above cell plates is used to collect H2 and O2 generated from charging and discharging evolutions.

Describe the function(s) of a battery Flame arrestor

Porous cap on jar used to provide a controlled release of charge gases and prevent foreign material from entering cell.

Describe the function(s) of battery Separators

Separators between the negative and positive plates are used to:

Electrically insulate plates and allow a path for charge gasses to escape to the top of the cell.

Describe the function(s) of battery Retainers

Retainers are used on the positive plates to keep active material on the lead-calcium grids.

Describe the function(s) of a battery Cell post

Used to connect cells together with intercell connectors in order to make a battery.

Describe the function(s) of a battery Intercell connector

Used to connect cell posts of adjacent cells together.

Describe the function(s) of a battery Service assembly

Used to sample electrolyte specific gravity, electrolyte temperature, and add makeup water

Lead dioxide (PbO₂) acts as positive electrode.  The soft electrode material is pressed onto a lead-calcium grid.  Plate straps are used to connect plates

Sponge lead (Pb) acts as negative electrode.  The soft electrode material is pressed onto a lead-calcium grid.  Plate straps are used to connect plates

Explain the electrochemical process of a lead acid battery in terms of the Battery Charge & Discharge equation

Pb   +    PbO₂   +  2H₂SO₄ <=>   2PbSO₄    +     2H₂0   + e’s

(–)plate, (+)plate, Electrolyte <=> (+)&(-) plates, water, electrons

Charged<=>Discharged

Explain the Voltage characteristics of lead acid cells and batteries

Voltage decreases at a gradual rate during discharge until the battery is no longer able to supply the required voltage (~rated end of discharge), then it drops off quickly.

Explain lead acid battery capacity ratings and the effects that discharge rates have on capacity.

Capacity depends on the number, design, and dimensions of plates and the quantity of electrolyte.

Amount of energy a fully charged battery delivers depends on discharge rate, temperature, and age of the cell.

Higher the discharge rate, the total ampere-hours the battery can deliver is decreased.  Higher the temperature, battery capacity increases and battery life decreases.

Explain the effects that temperature has on battery performance

Higher the temperature, battery capacity increases and battery life decreases.

Define Float charge

Define Equalize charge

 Returns the battery to a fully charged condition quickly

Explain the hazards associated with battery operation.

Battery electrolyte contains sulfuric acid and is considered a hazardous material and, as such, may have special cleanup and disposal requirements in the event of an electrolyte spill.

Batteries store an enormous amount of energy, generally, there is no over current protection or other means to disconnect a battery should a conductive device short-circuit the battery terminals.

Batteries generate hydrogen and oxygen gas during charging operations.  3-4% hydrogen concentration is combustible, >8% is explosive. 

State the functions of a battery charger.

1) Battery chargers convert alternating current to direct current to charge the battery

2) Supply normal power to DC system loads.