EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: nowlan on August 05, 2015, 02:58:57 pm
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Hello,
I was curious about some car battery analyzers. They claim to use conductance, which is 1/R from memory.
Battery University Link (http://batteryuniversity.com/learn/article/why_do_different_test_methods_provide_dissimilar_readings)
Some examples:
1. Cen-Tech (http://www.harborfreight.com/digital-automotive-battery-analyzer-66892.html) (Internals (http://weldingweb.com/showthread.php?44177-Review-Cen-Tech-Digital-Automotive-Battery-Analyzer-66892))
2. Ctek (http://www.ctek.com/au/en/chargers/Battery%20Analyzer)
3. Solar (http://www.amazon.com/BA5-100-1200-Cranking-Electronic-Battery/dp/B0017R5EQK)
Would I be able to do the same with a multimer or ESR meter?
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Yes. Just insure your AC source has a blocking capacitor to protect the signal output circuitry. The battery's output impedance correlates poorly with Ah, but its an index of battery aging. Its more accurate to burn test a battery.
EIS or Dielectric spectroscopy is basically a spectral signature of a healthy vs unhealthy battery. Instead of using one frequency as the standard AC test, it uses several frequencies. You could consider the battery as a variable capacitor, as it ages the capacitance changes so the frequency response changes too. AFAIK, no one knows the optimal frequency or combinations of them. This is probably what the cadex patent is about.
http://lygte-info.dk/info/Internal%20impedance%20UK.html (http://lygte-info.dk/info/Internal%20impedance%20UK.html)
http://www.flippers.com/esrkthnt.html#battery (http://www.flippers.com/esrkthnt.html#battery)
I wouldn't be surprised if the practical task is to inject a square wave instead of sine and getting the Fourier signature, as an index.