Thread: New Product ESR / IR Meter fo Lipos
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Old Oct 20, 2010, 03:20 PM
Wayne Giles is offline
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[[SIZE="2"]QUOTE=mrforsyth;16338611]Nice work Wayne.

Quick question - Have you had the opportunity to corroborate the readings from your meter with any of the commonly used hobby grade chargers that incorporate IR measurement features? (FMA CP10, PL8, iChargers, etc.) And with greatly varying cell capacities? Also wondering how the results compare with a lab grade kelvin meter...

I (among others) have long complained that C ratings are basically useless since there is no test standard. Sadly, C ratings have proven to be an extremely effective marketing tool however as most modelers are not aware that they are very arbitrary. As such, I have been using cell IR as my primary performance indicator for the last few years as it's much simpler than firing up my CBA.

I would be much happier if lipoly manufacturers would print measured cell IR on their packs rather than arbitrary C ratings. This will obviously never happen though as it would likely expose the largest lipoly vendors in a less than favorable light.

Mark[/QUOTE]

Thanks Mark,

The only Charger I have which reads IR is a Hyperion EOS0610iNET which is a great charger but not very good at measuring IR. It reads between 150 and 250% of the IR I measure, varying with pack size and other factors which I cannot quantify. So much so that I quickly gave it up as a measurement source.
The meter gives the same results that I see in power testing ie the figures agree with the initial drop when the a controlled CC load is applied. Obviously I have checked this against the step change on a memory 'scope using reasonable length pulses of significant load, 10- 20C. I don't have a lab grade Kelvin meter, but have calibrated 10 and 45 milliohm resistors which I use to calibrate the 'Cell' and 'Pack' ranges respectively, and all the meters so far have shown figures within 1% on the Cell range and 3% on the Pack range. Latter is more difficult to be precise as it is not a Kelvin measurement so we have a (variable) connector contact in series.
I agree with you about "C" ratings. They were a joke a few years back and I was beginning to think they were more realistic when claims were 25 and 30C. I now think we are into another lunatic claiming era.
Whilst I agree with your last paragraph, the pack must be soaked at a known temperature (25deg.cent/77deg.F?) and given time to settle if you are comparing packs.
When looking for degradation between cells within a pack this is obviously not a problem and the advantage of the meter it gives an instant answer.

Wayne
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