Is conductance a reliable measure for checking usability of used and new consumer and camera batteries? What about button cells and laptop battery packs? If not, why does it work on automotive and gel batteries? Thanks for all replies. If there is already a thread of FAQ on this subject, I apologize for this posting, and would appreciate a LINK to such threads or websites. Using a multimeter's conductance tester for checking small batteries OK?
Using a multimeter's conductance tester for checking small batteries OK?
Feb 20, 2005
2 Replies
I have a gadget that I built to test lithium ion batteries at the junk store. It's a DMM across the cell with a nicad pack, limiting light bulb and switch in series across the cell. Read the voltage, push the switch, read the voltage again. The difference gives you some idea of the internal series resistance of the cell IF they have similar state of charge. I've found this a reasonable way to match cells. YMMV, don't do this at home, professional driver closed course, danger Will Robinson... mike
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Battery internal resistance (conductance - 1/resistance) is often measured with AC techniques, such as applying a small sine or squarewave current waveform and measuring the ac component of the battery voltage.
Unless you have a multimeter which measures conductance this way, do not use a multimeter on the ohms or conductance range. The readings won't mean anything and you can burn out the meter.
Google for "battery resistance" and "battery conductance" and you can spend hour learning.
Roger
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