Which IR Range is Acceptable for 18650 Cells?

Once you get into the world of sorting/testing 18650 Li-ion’s it’s all about the infrared (IR) region in which to do the tests, this affects how good (better or worse) a job your sorting machine can make of it – other than that (doing the sorting) it couldn’t give a toss for such niceties as voltage and capacity and kickassness resistance. What is IR and why test it?
Infrared tests are a fast and easy hack non invasive way to read (among other things) the internal resistance (IR) of 18650 cells. IR is a significant part of battery ‘goodness’ and needs to be kept relatively smooth across a bunch of cells so as not to cause problems across the pack. Hookingup batteries in series in steel means pakcs also need to be matched in IR specs for just such reasons – especially for performance applications like EV’s. Typical IR Range for 18650 Cells
Most 18650cells sit somewhere in the IR range of 10 milliohm (mΩ) to 100 mΩ, although this varies a littleCells with lower internal resistance (IR) are more efficient, hence more likely to outlast their rivals. A good quality 18650 for use in an electric vehicle, or for power storage systems, will show up with a generally lower IR value than one used for tiny consumer devices. Measuring the IR of a cell when sorting and grading them gives you some possibly useful info, but is something you should not rely on.
Choosing the Correct Battery “Sorting Machine” For 18650 Cells
Things to take into consideration when your choosing a sorting machine for 18650 cells specific to what IR measuring range to go with:
– Measure range—Bigger measuring ranges for IR are more suited to the better performing cells, but a machine that gives a wider IR range is going to be of more good with other batteries. Obviously, the bigger the capacity the less the sorter will work in whatever other role but high density production.
– Throughput—Make sure the sorting machine can handle how many you want, and sort of go with one higher than that throughput wise.
– How fast of a sorting machine do you want? Some are made very speedy if that is of more of a concern. Good for high volume production.
– Some of the sorters will have features like-auto calibration in addition to a better UI, etc. and will possibly improve the sorters overall performance.
– As a manufacturer or recycling park if you want to find out the good and poor quality cells, a built in IR test is certainly going to help with this. This of course is mainly for quality control purposes but of also labelling and grading the cells.
In the sorting house recycling plant, so this is going to assist in determining which cells need to be replaced and sent to the lithium recycling facility, versus cells with proper III’s that still work properly. This is going to clear things up too when it comes to picking a working cell for a project.
Capacity grading is also going to basically be a more thorough evaluation of a cells overall performance characteristics as well. When executed along with the IR test, and possibly by other testing methods as well too, you get more of a clearer overview of a18650’s potential.