3550 Battery HiTESTER Series
10
6 Resistance Measurement…...………………………………………
Q1. Can the impedance of a battery
not be measured with a DC type
ohmmeter?
A1. A DC type ohmmeter applies a constant DC
current and measures the voltage reduction
caused by the load to determine the
resistance. In the case of a battery, its
electromotive force prevents correct
measurement of impedance using such a
setup. In order to eliminate the influence of the
battery's electromotive force, an AC type
ohmmeter must be used.
Q2. Why is testing conducted with a
1kHz AC current?
A2. There is no standard or rule that requires
battery testing to be conducted with a 1kHz
current. The reason why testing is
conducted at 1kHz is due to the current flow of
existing AC- type resistance meters. AC-
type resistance meters were developed for
measuring contact resistance. Contact
resistance meters conform to IEC512- 2,JIS C
5402,and JIS C 5441,and one item in these
standards calls for testing to be conducted at
1kHz. Accordingly, the majority of AC
resistance meters are designed for 1kHz
testing. Because commercially available
resistance meters are frequently used for
measuring the internal resistance of a battery,
a considerable amount of data on
measurements taken at 1kHz has been
accumulated. Therefore, in order to maintain
compatibility with this previously accumulated
data, we decided to design the 3550 series to
take measurements at the 1kHz frequency.
While we realize the internal resistance of a
battery is frequency- dependent, there are
indications that this characteristic is relatively
flat between 100Hz and 1kHz.
Q3. Can the range used by the 3550
series be changed?
A3. It is not possible at present to change the
testing range.
Q4. Can the testing current be
changed?
A4. If the testing current is changed, the voltmeter
gain must also be changed at the same time.
Changing the gain is an extremely delicate
proposition, since it is accompanied by
changes in the temperature characteristics,
noise characteristics, etc. Therefore, it is not
possible to change the testing current. We
will study this issue when we develop future
AC m ΩHiTESTERs.
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