"how much ofinternal resistance should you tolerate?"
That my friend is the 64 Thousand dollar question.
There are many opinions out there as far as IR is concerned and opinions count as some of them are tied to real life experiences.
There are several on this board that are researching this question with much fervor and are working on an answer.
I am one of those. I have at this time only collected several weeks of data regarding "Heaters" IR,SD and the testing procedurethat I have used to come up with some datasets.
This is by no means complete and unfortunately not ready to publish as we do not have enough data as of yet, to come up with a proper conclusion. We are at a theory stage as of yet.
So the best I can say at this point is stay tuned and some definitive best practices will come of this I am sure.
The best info I can give you for now is that preliminary data shows most (not all) cells which are measured with a Kelvin 4 wire IR reader that are over 70m?tend to be heaters esp. the Sanyo brand.
Thats all I have for now.
I Am sorry to disagree in the fact that Opus ist able to give accurate IR.Korishan said:Yes, there are several devices. A standard DMM can measure them. The opus and liitokala, and i'm sure others, can test the IR.
The higher the IR, the more difficult it becomes to pull higher amps. Most IR ratings come into place at .5C or more. If you parallel enough together, you won't even get .5C, but closer to .1C. Or, about 300mA per cell. This is so low that IR doesn't have much of an effect.
Think of IR as water, energy required to move as Amp, and your movement as Capacity. If you move slowly through water, you can do it all day long with little energy use. Try to walk fast, and it becomes more difficult. Try to turn, and you burn your energy rather rapidly. As you can see in this real world life size example, IR has a major effect the faster you move, or with the cell the more Amps you try to pull.
batteryq said:Thank you guys for all the great info!
I too find some of the devices which claim to be able to measure IR are not as accurate as one would hoped. I used Liit and zanflare, same battery the IR reported are about 50-100mOhm different, with zanflare always higher than Liit. I am not sure which one to trust.
Wolf said:Here is a spreadsheet with the IR and mAh results of 4brand new Samsung 25R cells tested with 6 different testers.
The commercial TZ1030 is used as a reference that I trust.
The LiitoKala and the XTAR Dragon seem to be the closest.
Now I do notice that when I check recycled cells esp. the ones that have the remains of the nickel artifacts on the positive and negative terminals the readings are definitely different. Much higher in most cases on all the testers.
That being said the LiitoKala and XTAR Dragon (with its separate probes) seem to still be really close.
batteryq said:Can't wait for your testing result!
Chablis_m,Chablis_m said:Great Job!
We really need to consider how we link such info to the cell database
Maybe we don't need a full chart for every cell but at least the crossover point