Any Battery Guru's?

HI
Although the unit may be ""reasonably accurate"". The best method I have found for wet lead acid is load tester[carbon pile ] and hydrometer . Many load testers will have cca and amperage scale . The amperage scale vs the voltage scale is compared to verify .Typically around 300amps [600 CCA] at at least 9.5 volts is an ok unit .
Hydrometer [approx.] over 1.250 is ok near full
Static voltage anything over 12.6 is ok
After many years the above is a little more accurate than the computer calculation method.
After all said and done batteries can and do sometimes exhibit unusual unexpected behaviour . These situations are hard to predict by any method .
So I guess this leaves us back at the beginning ha ha .
Hope this adds to your knowledge .
Cheers
swampfox

Hi Phil,

Using 'battery impedance' as a reference to battery condition is somewhat indefinite. It does have some value as a referential technique where changes in measured value are compared.

I have had useful results in managing large static battery banks by applying a load then measuring voltage across each cell where a significant high cell voltage may indicate high cell impedance and probable cell deterioration. Cell replacement can then be considered, but this is not practicable with a normal six cell 12v automobile battery.

Your analyser may be useful to compare a particular battery's impedance with previous records to indicate failing performance but care would need to be taken that each test was performed under the same conditions of temperature, charge state etc.

A more reliable assessment for a deep-cycle battery is obtained by measuring the battery's capacity by performing a controlled ampere hour discharge and comparing to manufacturer's specification and to previous test. This places the focus on capacity rather than high current ability.

It is difficult to obtain adequate engineering specifications from automobile battery manufacturers as their published data is limited to user interest such as CCA, Ah etc. This sort of information is more easily obtained from manufacturers in regard to industrial batteries.

To respond to your specific question, an internal resistance of "15.98 milliOhms" is suggestive of good condition in a 100Ah battery.

This Telstra Paper may provide some indication of the limitations and difficulty of assessment by measured battery impedance.