Lead-Acid Storage Batteries
There are numerous applications for the use of lead-acid storage batteries. They range from
the extremely large battery systems used in load leveling by electrical utility companies to the
relatively small batteries used in hand tools. Batteries may need to undergo deep and
frequent cycling such as those used for electric vehicle power or they may remain on "float"
as in an emergency lighting application and only rarely be discharged. Clearly, these
applications cannot all use the same battery. Restraints on parameters such as operating
temperature, desired capacity, voltage and power requirements, etc., affect the type of
All the above considerations are taken into account by determining the battery's duty cycle.
The duty cycle is the required operating parameters of a cell or battery including factors such
as charge and discharge rates, depth of discharge, cycle length, and length of time in the
standby mode. The duty cycle must be known and included in the battery procurement
specification. The duty cycle and battery chosen will also determine the type of charger used.
More details on matching chargers to batteries and applications are included in later
paragraphs. More information on duty cycles is included in the section entitled "Sizing and
The major categories of lead-acid battery applications are starting, lighting, and ignition
(SLI); industrial, including traction and stationary applications; and small portable
equipment. A brief description of each type is included below along with example uses of
Starting, Lighting, and Ignition
SLI batteries are used by most people every day and are produced in greater numbers than
any other type of lead-acid storage battery. These are used to start automobiles and most
other kinds of internal combustion engines. They are not suitable for deep discharge
applications, but excel for uses needing a high current for a brief time. They are usually
charged in a "partial float" manner, meaning that the battery only receives a float charge
while the vehicle is running. A cutaway view of a typical SLI battery is shown in Figure 12.
SLI batteries are usually of the flat pasted plate design.
Industrial batteries generally have the largest capacity of the three major categories of lead-
acid batteries. Industrial batteries are used for vehicle traction and stationary applications.
Traction batteries are used to provide motive power for electric or hybrid vehicles. The
major emphasis on traction battery design is the necessity of a high capacity to weight