Originally Posted by KRProton
Purchased and waiting for delivery of my new ESR meter (thanks Wayne!).
For valid comparisons from pack-to-pack, I understand it is paramount to be consistent with battery temperature. I understand the standard temp is 72F (71.6). To that, how do you bring your LiPos to this temp for testing?
I used to use 25*C (77*F). as a standard temperature only on the basis that 25*C is usually the ambient temperature quoted in specifications of most electronic components. Mark Forsyth pointed out, very reasonably, that the average house or apartment emperature was more like 22*C which really means that is what his house is set to!!! I am forced to agree so we changed the measurement temperature to that value.
So the answer to your question is that you leave it to settle for 2 hours at least in that ambient. Being in the UK and having an outside workshop which generally runs well below that, I have converted a small drink cooler/ heater into a temperature controlled enclosure and set it go 22*C. Again I soak them for 2 hours before test.
Re your later post, I am away at present so don't have access to records but 4.2milliohms does not sound too low for a good 1800 cell at 22*C. I have seen a several 2200 cells at <3.5 milliohms which pro rata is about the same.
Remember that the Lipotool is just a guide and that if you preheat your lipos, the IR will be lower and you can then take more current without overstressing them.
This is within sensible limits of course.
Also be aware that some of the latest lipos claiming very high C ratings, really just have a higher temperature coefficient of their IR which means that you can take higher currents, but the downside is that they do not perform well at lower and moderate currents.