Specifications

64
Battery
Type
Cost
Size (inches)
Lead
Times
Performance
Voltage
output
Recharge
Cycles
Alkaline
$12
Size of standard
9V
<1 Week
Poor; limited
recharge,
inconsistent
performance
over lifespan
9V
Very low
Nickel
Cadmium
$10.50
5.2 x 1.7 x 0.87
<1 Week
Good
6V
Many
cycles
Nickel
Metal
Hydride
$20
3.38" x 2" x
0.57"
<1 Week
Good
6V
Fewer
cycles
than NiCd
Lithium
Ion
$20
3.54x1.97x0.394
<1 Week
Good
7.4V
Limited
Lead Acid
$20
3x2x1
<1 Week
High discharge
acceptable
6V
Limited
Zinc
Nickel
$15 for
four (4)
Size of standard
AA
<1 Week
Excellent for
high discharge
1.6V
(single)
High, if
charged
correctly
Table 2.11.7-1: Comparison of batteries
2.12 Charging Circuit
Since a rechargeable battery will be used in the portable unit for power away
from the base unit, there must be a method of recharging the battery. There are
several options available for such a task. However, the unique considerations of
the portable unit and project as a whole will require an examination of various
charging solutions to choose the optimal solution for this project.
While rechargeable batteries have many unique properties themselves with
respect to aspects such as number of recharge cycles, capacity, safety, size, and
many other criteria, their unique charging needs can also be exhaustive. Each
battery requires its own method of charging, and has various tolerances to such
general events as insufficient power, too much power, high temperature, and
other power events.