The successful application of lead-acid batteries results from
careful consideration of application characteristics, proper matching with
battery capabilities, and observance of certain guidelines and recommendations
for battery usage. Military battery applications impose a wide range of
electrical, mechanical, and environmental demands on the battery.
Consequently, battery manufacturers must adopt design, process, and quality
standards that often exceed those for commercial products.
The very first step in user battery selection is careful
consideration of the battery characteristics demanded by the application.
Applications for lead-acid batteries can be divided into three broad
• Standby (Float) Service
• Starting/Lighting/Ignition (SLI)
• Cycle Service.
These categories can be further subdivided into specific
applications. Application requirements lead to wide differences in battery
characteristics. These differences necessitate specific discussion of each
Standby (Float) Service Applications
The objective of all standby battery systems is to provide an
uninterruptible supply of power to the electrical system being backed up.
Standby batteries go on discharge immediately upon interruption of primary
There are four major classifications of standby battery
systems as shown in Table 5-1. Each of these classifications has unique design
characteristics to match application needs. Table 5-1 shows the application
needs for each of these four classifications.
TABLE 5-1. CLASSIFICATION AND NEEDS OF STANDBY SYSTEMS
|AC or DC System
||Up to 5, steady
||Up to 1000, steady
||Up to 2500 pulses,
|Up to 3000 varying|
|Support Time (Hours)
||1 to 8
||3 to 20
||Up to 8
||Up to 1,|
||Up to 38 Ah,
|Up to 8000 Ah,
|Up to 3000 Ah,
|Up to 5000 watts,|
|Battery Life (Years)
||3 to 5
||Constant Voltage |
Applications of SLI batteries are shown in Table
TABLE 5-2. APPLICATION OF SLI
||6, 12, or
Voltage and/or Current|
Batteries in this class are used primarily for engine starting.
This may be for either internal combustion engines or turbines. For the
internal combustion engine, the battery duty cycle is characterized by a short
pulse discharge at a very high current for a short period, immediately
followed by the battery being recharged. Depth of discharge for each start
cycle is usually shallow. In a turbine start, the battery must deliver a very
high initial current, typically over 1000 amperes, to overcome the inertia of
the turbine as it starts to spin. This current draw tapers rapidly as the
turbine gains speed. Ten to 20 seconds into the start cycle the current output
of the battery may be in the 400 to 800-ampere range. The turbine start is
typically 40 to 60 seconds in duration. There is a critical period during the
start where failure of the battery may severely damage or destroy the engine.
Coupled with this is the common requirement, particularly in aircraft, that
the turbine starting battery be extremely compact and lightweight. It is
critical that turbine engine starting batteries be of the highest quality and
A secondary use of SLI batteries, in most applications, is to
provide reserve or emergency capacity. In vehicles, this allows the user to
operate lights, radios, and other equipment for a short period without the
need to run the engine. In aircraft, this may be the only source of power to
operate the instruments and controls, or lower the landing gear in case of
on-board generator failure.
Cycle Service Applications
Batteries in cycle service are used to power:
• Electric vehicles such as lift trucks and other material
• Portable devices such as lanterns and tools
• Electric devices in a photovoltaic system during periods of
In each of these applications, the battery is the
primary energy source. It must be capable of delivering sufficient power to
the vehicle or device for its intended duty cycle before requiring recharge.
Batteries in these applications may have different load profiles and may be
discharged to different depths as part of their duty cycles. Typically, the
number and depth of cycles limits the life of these batteries. Hence their
life is expressed in cycles rather than years. Applications of cycle service
batteries are shown in Table 5-3.
TABLE 5-3. APPLICATIONS
OF CYCLE SERVICE BATTERIES
||Normal 8 to
Current, or Constant
Voltage (Also trickle
charge during nonuse)
Common Application Needs
Battery users in the three broad application categories must
consider environmental conditions, charging requirements, and safety in
addition to electrical requirements in the selection, sizing, and operation of
the battery. Environmental conditions and charging requirements are described
below. Safety considerations are described in Section 5.7.
Some batteries are housed in shelters, even in air-conditioned
rooms. They are installed and operated so there is no mechanical shock.
Vibration is limited to seismic events (earthquakes). However, others are
installed in a manner that exposes them to extremes of temperature, altitude,
vibration and shock. Temperature is the most important environmental variable
because it can affect both life and performance. Performance varies directly
with temperature over most of the operating range. Battery life varies
inversely with temperature.
The way the battery is charged can influence life as well. Many
applications require long-life batteries. Charging in these applications is
restricted to current-limited/constant-voltage charging. A discharged battery
is charged at the current limit initially until battery voltage approaches the
constant voltage limit. When the voltage limit is reached, the current will
taper down and stabilize at the finishing current. In standby batteries, the
float voltage is the constant voltage limit.
In those cases where the battery must be charged quickly, a
variation of this charging regimen is used. The constant voltage is held at a
higher value for a pre-determined time and then lowered to the float voltage.
This variation ensures that adequate back-up power is available to the load if
another primary power interruption occurs. A slight penalty is incurred in
battery life. In vented cells, water loss is increased. In valve-regulated
cells, end-of-charge temperature is higher.
Constant-current charging is used to further speed up recharge
of discharged batteries. Again, the penalty is water loss in vented batteries,
gassing and heating of valve-regulated batteries and shortening of life.
Constant-current charging should be avoided in all but the most rigorous cycle
service applications such as lift trucks. In these cases, a time limit must be
imposed on constant current charging.
Proper definition of application requirements can be
achieved through a comprehensive checklist which can assist both the user and
the manufacturer in selecting the right battery for each specific application.
It should cover electrical, mechanical, and environmental considerations. See
Table 4-1 for a sample
checklist. There may be other special needs for a specific application that
are not included in this