1. Battery Fundamentals
Chapter 26

2. Objectives Describe battery parts and operation
Understand how a battery converts chemical energy to electrical energy
Explain battery capacity ratings
Select the correct battery type to use in a variety of applications

3. Introduction Battery: heart of a vehicle's electrical system
Converts electrical energy into chemical energy
Converts chemical energy back into electrical energy
Provides power to accessories
Supplies current to the starter
Acts like a capacitor
Starter motor: largest load
Draws more than 100 amperes
Battery voltage is low after use

5. Battery Parts and Operation
DC voltage
Produced when two different metals are immersed in an electrolyte solution
Automotive batteries
Plates provide 2.1 volts
Fully charged positive plate: combination of lead and oxygen (i.e., lead dioxide)
Plates: grids with horizontal and vertical bars
Battery's case filled with electrolyte mixture

6. Battery Parts and Operation (cont'd.)
Battery cell
Consists of a packet of several positive and negative plates
Battery terminals
Connections are made of lead
Some batteries have side terminals
Battery case
Most are constructed of lightweight plastic
Cell caps
Most battery tops have removable cell caps

7. Battery Recharging and Discharging
Current flows to battery from charging system
Battery explosions injure 15,000 people a year
Battery discharging
Positive and negative plates become alike as the battery discharges
Process is reversed during recharging
After repeatedly charging and discharging
Active material on the cell plates is worn

9. Battery Capacity Ratings
Battery capacity is related to:
Surface of plates
Weight of active materials on plates
Strength of electrolyte solution
Cold cranking amps (CCA) rating
Most common method of rating batteries
Some manufacturers rate batteries in watt-hours
Reserve capacity
Indicates how long a vehicle can be driven after a charging system failure

10. Battery Types Batteries are designed for specific uses
Deep-cycle: original battery design that was used in cars for many years
Maintenance-free: have cell plates made of a slightly different material
Low-maintenance: revision of the maintenance-free battery

11. Battery Plate Size Battery size is related to its reserve capacity
Vehicles with larger engines and more accessories require batteries with more plate surface
Recombination batteries
Sealed batteries using electrolyte gel or microporous nonwoven glass
Absorbed glass mat batteries
Do not use free-liquid or gel electrolyte

12. Battery Selection BCI lists group numbers Considerations
Indicate physical size of batteries
Considerations
Must fit the battery box
Posts must be on the correct side of the battery
Battery holddown must fit the battery
Battery cannot be so high that it shorts on the hood

13. Battery Service Life Average battery Effects of sulfation
Service life of three to five years
Life is determined by amount of material shed from surface of positive plates
Effects of sulfation
Usually reversible
Effect of temperature on batteries
Batteries do not work well in cold weather
Engine becomes harder to crank
Battery that is not fully charged will freeze easier

14. Battery Cables
Must be large enough to carry all current demanded by starter
Large cable is connected directly to the starter
Cables for 12-volt systems are usually four or six gauge
Battery terminal clamps
Made of plated steel, brass, or lead

16. Battery Holddowns Battery must be held in its tray
Can fall out as the car travels over bumps
Excessive vibration can harm the battery
Holddowns are made of steel or plastic

17. Reasons for Battery Failure
Include:
Damaged battery case can leak electrolyte
Undercharging can cause sulfation
Overcharging can cause buckled and warped plates
Vibration can cause more material to be shed from plates
Internal shorts between the plates can cause a dead cell

18. Hybrid Electric Vehicle and Other Battery Types
Other types of batteries include:
Nickel metal hydride batteries
Subject to memory effect
Lithium-ion batteries
Term used for all batteries that use lithium
Typical hybrid battery
Most hybrid automobiles use NiMH batteries
Paper membranes absorb electrolyte
Hybrid battery pack gets hot
Has air cooling system