Battery Selection 250

This class discusses the factors on which batteries are rated and describes many of the most common battery types. Includes an Interactive Lab.


Class Name:
Battery Selection 250
This class discusses the factors on which batteries are rated and describes many of the most common battery types. Includes an Interactive Lab.
Number of Lessons:
Additional Language:

Class Outline

  • Objectives
  • What Is a Battery?
  • Battery Composition
  • Importance of Batteries
  • Battery Ratings
  • Reserve Capacity
  • Cranking Amperage
  • Physical Requirements
  • Cost and Replacement
  • Environmental Conditions
  • Primary Cells
  • Lithium Cells
  • Nickel Cadmium Cells
  • Nickel Metal Hydride Cells
  • Lead Acid Cells
  • Battery Testing and Safety
  • Summary


  • Describe batteries.
  • Describe how a battery is composed.
  • Describe the many uses of batteries.
  • Describe how batteries are rated.
  • Describe reserve capacity.
  • Describe cranking amperage.
  • Describe the physical requirements for batteries.
  • Identify factors affecting a battery’s true cost.
  • Describe how environmental conditions affect battery life and performance.
  • Distinguish between the main types of primary cell batteries.
  • Describe lithium cells.
  • Describe nickel cadmium cells.
  • Contrast NiMH to NiCad batteries.
  • Describe lead acid batteries.
  • Describe battery testing and safety.



Vocabulary Term Definition
alkaline A primary cell battery that is small, lightweight and durable. Because alkalines are inexpensive and relatively efficient, they are currently the most common battery type.
amp hour The most common unit used to express battery capacity. Amp hours are a product of current and time.
battery A device that converts chemical energy into electrical energy. Batteries are a source of direct current.
button cell A small, button-like battery that provides power for watches and very small devices.
capacity The amount of energy a battery can store. If battery materials are the same, capacity is directly linked to volume.
carbon zinc The first practical primary cell. Carbon zinc batteries are still used, but they have less capacity than alkalines.
cell A single unit of a battery.
cold cranking amperage A rating similar to normal cranking amperage but measured at 0°F.
cranking amperage A rating used to measure how much start-up current a battery can produce before voltage drops below a usable level. CA is measured for 30 seconds at 32°F.
cycle A complete battery discharge and a full recharge.
cycle life The total number of cycles a battery is capable of producing before it fails.
discharge curve The charting of the voltage level of a battery as it drops off during use. Internal resistance causes the drop in voltage.
downtime The period of time when a machine is not operating or producing.
electrodes The terminals, or metal ends, in a battery that have a positive or negative potential.
electrolyte A substance that functions as a medium for electrons to flow from the negative to the positive plates in a battery.
electromotive series A list of metals in order of most reactive, or most likely to give up electrons, to least reactive. These metals are used in batteries.
energy The ability to do work. Energy is measured in Wh and is expressed as the product of power and time.
energy density The ratio of a battery's energy-delivery capability to its weight or volume, measured in watt-hours per pound or watt-hours per cubic inch.
flat discharge curve A favorable battery condition where voltage remains relatively steady until the battery is nearly discharged.
fossil fuel Any naturally occurring organic fuel formed in the Earth’s crust, such as petroleum, coal and natural gas, that can be burned to release stored energy.
gassing A buildup of flammable hydrogen within a battery, usually due to overcharging. Some batteries have pressure release valves to prevent gassing.
gel cell Another name for a sealed lead acid battery.
hot cranking amperage A rating similar to normal cranking amperage but measured at 80°F.
hydrometer A device used to measure the specific gravity of a fluid, such as the electrolyte in a battery.
internal resistance The natural ohmic value of the electrodes in a battery. Internal resistance causes a battery's voltage to be lower with a load than without a load, and to decrease over the course of discharge.
lead acid One of the more common secondary cell battery types. Lead acids are rugged and inexpensive per watt hour.
lithium A name used to describe several different types of batteries that use energy-dense, lightweight, and highly reactive lithium. Though relatively expensive, lithium cells are quickly becoming a popular battery choice.
lithium ion A newer, rechargeable lithium-based battery. Though volatile and expensive, lithium ion has very high energy density and is increasingly popular.
lithium polymer A newer, rechargeable lithium-based battery. Lithium polymer was developed as a lower cost, more stable version of the lithium ion cell.
memory effect A phenomenon occasionally seen in nickel-based batteries that are consistently recharged before they are fully discharged. These batteries have been shown to "remember" the point of premature recharging and lose capacity before they should.
milliamp hour A unit of battery capacity for smaller cells. A milliamp is one thousandth of an amp.
nickel cadmium A common type of secondary cell battery that can go through thousands of charging cycles. Nicads have a good flat discharge curve, but can potentially suffer from the memory effect.
nickel metal hydride A type of secondary cell that is becoming a popular alternative to NiCads. NiMH batteries are more environmentally friendly and show a reduced memory effect.
power The product of current in amps and voltage in volts. Power is measured in watts.
primary cell A type a cell that cannot be recharged. Primary cell batteries are usually thrown away once their charge is spent.
renewable energy A type of energy like sunlight or wind that is naturally and continually replenished without being depleted.
reserve capacity The number of minutes a battery can maintain a useful voltage under a 25A discharge. Reserve capacity is often a truer test of battery life than amp hours.
sealed lead acid A type of secondary cell with a semisolid electrolyte that eliminates some of the drawbacks of regular lead acid batteries. While more expensive, SLA batteries can be used in any position and require little maintenance.
secondary cell A type of cell that can be recharged. Running current through a secondary cell restores its chemical potential.
self discharge Capacity loss during storage due to the internal leakage between a battery's metal plates. All batteries eventually self discharge.
service life The length of time a battery is expected to be in operation before being replaced.
shelf life The length of time a battery can remain in storage without losing its energy capacity. The metal plates eventually leak and react with each other, even though not in use.
sloping discharge curve An unfavorable battery condition where voltage drops almost immediately and gradually decreases as a battery is discharged.
specific gravity The ratio of the volume and weight of a substance to an equal volume and weight of water. Specific gravity is generally a good judge of a substance's electrochemical usefulness.
sulfation An effect of overcharging or other environmental conditions in lead acid batteries that leads to permanent capacity loss. Flakes of lead sulfate break away from the plates and fall to the bottom of the cell, where they can no longer react and produce energy.
total cost of ownership A set of factors that takes into account reliability, maintenance time, and replaceability in addition to initial cost. TCO is a truer judge of a battery's expense.
volume The amount of three-dimensional space that an object occupies. Volume is measured in cubic inches.
watt A unit used to express electrical power. A watt is the product of amps and volts.