Civil Engineering Reference
In-Depth Information
FIGURE 10-17
Lead-acid battery capacity with discharge time.
The discharge rate influences the lead-acid battery capacity, as shown in
Figure 10-17
.
The shorter the discharge time (i.e., higher the discharge rate),
the lower the Ah capacity the battery can deliver.
The lead-acid cell voltage is 2.0 volts nominal, and the internal resistance
is around one milliohm per cell. The cycle life is 500-1,000 full charge dis-
charge cycles for medium rate batteries. The operating temperature range is
between -20 to 50°C and the survival temperature is -55 to 60°C.
10.6
Battery Design
The battery design for given application depends on the following system
requirements:
•
voltage and current.
•
charge and discharge rates and duration.
•
operating temperature during charge and discharge.
•
life in number of charge and discharge cycles.
•
cost, size, and weight constraints.
Once these system level design parameters are identified, the battery
design proceeds in the following steps:
•
select the electrochemistry suitable for the overall system require-
ments.
•
determine the number of series cells required to meet the voltage
requirement.
•
determine the Ah discharge required to meet the load demand.
