Hioki 3550 - Page 24

3550 Battery HiTESTER Series
24
resistance.
1
Therefore, we have developed a secondary battery internal resistance tester that
utilizes low resistance measurement techniques, and we measured internal resistances of
secondary batteries with varying the state of those.
2. Overview of Secondary Batteries
A secondary battery is one that can be used repeatedly after recharging, and differs from
primary batteries, such as manganese dry cells, that cannot be re-used once they are
discharged. Another distinction of secondary batteries from primary batteries is that secondary
batteries are capable of discharging large current; as a result, they are used for equipment that
requires large current. Typical secondary batteries are lead-acid batteries and nickel cadmium
(Ni-Cd) batteries. However, in order to address environmental concerns and the need for
batteries that can power smaller devices for longer periods of time, new nickel metal hydride
(Ni-MH) and lithium ion (Li-ion) batteries were developed and put into use; these batteries are
smaller, provide a large capacity, and pose little danger of polluting the environment. Table 1
shows characteristics of the secondary batteries described above. This table lists
characteristics for each type of battery, including voltage per cell, the energy density by mass
(Wh/kg) and the energy density by volume (Wh/l). In this table it is found that lithium ion
batteries offer a high energy density and excellent performance. In practice, the type of
secondary battery that is used in a particular application depends on the requirements of the
equipment in which it will be used.
Table 1. Characteristics of Typical Secondary Batteries.
2
Energy density
Battery type
Voltage
Wh/kg Wh/l
Features (V/cell)
Lead-Acid 2.0 30 - 40 70 - 100 Low cost, high reliability
Nickel cadmium
(Ni-Cd)
1.2 45 - 70 100 - 150
Capable of rapid charging/discharging,
withstands excessive charging and
discharging well
Nickel metal
hydride (Ni-MH)
1.2 50 - 65 150 - 200
Superior characteristics compared to
nicad batteries without polluting the
environment
Lithium ion (Li-ion) 3.6 60 - 90 150 - 220 High energy density, high voltage