From what I've been able to find/determine about some of the newer hand-held
battery analyzers (approx $300 price range), this method of applying a small
load and then pulsing the battery is how the displayed results are
calculated.. allowing a thorough test to be performed by a small instrument.

I've had capacitor ESR meters for years, but they're generally not reliable
for battery testing, and some designs just won't tolerate an input voltage
at the test input.
Many cap ESR testers' operating frequencies range from 1k to 100k (single
frequency, not variable or selectable) possibly with the majority of testers
utilizing 1k to 10kHz.

I bought an inexpensive dedicated (1kHz) digital battery impedance meter a
while ago, speculating that it's measurement capabilities would (be useful)
help determine the matching/reliability? of individual rechargeable cells..
and possibly the condition of health of lead/acid batteries, but I haven't
investigated the meter's practicality as far as LA/car batteries after
seeing that the meter's readings were essentially only comparison readings.

From what I think I understand about similar testers (capacitance value,
ESR, current leakage etc) they're essentially AC voltmeters, and the lower
cost/non-microprocessor types generally use an IC for dual slope
integration? to establish a reading from an internal/predetermined
sample/component.
It seems that the meter's usefullness would mostly be of use for comparing
readings of nearly identical cell/battery types, but otherwise just a tool
to gather readings which could be useful for statistical data (which may or
may not be useful after many entries).

--
WB
..........


"Jim Wilkins" wrote in message
...

Interesting.

The test I've seen and done for battery impedance is to measure the
voltage at a steady low-level current, then pulse on a higher load and
capture the voltage and current waveforms on a digital storage scope.
The impedance is the slope of the line between the low and high
current V and I, at a place on the waveform chosen by the battery
engineer. The higher frequency effects which are relevant to PWM motor
drivers are easily removed with capacitors. The low frequency
impedance (mostly resistance) is a good measure of the condition of
the battery.

jsw