I came across this answer How do I test rechargeable batteries? to the question of how to test rechargeable AA batteries and plan to try it. What I am wondering is how to apply this to other types of batteries. In particular, I have something that uses a pair of CR123 Li-Ion batteries sealed together in series to make a single rechargeable battery that is supposed to produce 7.2 volts and have a capacity of 500mAh or 3.6 watt/hours. How much resistance should I use to test it and what results should I expect both initially and after waiting a few days? What voltage should I consider to be too low for the battery to be considered healthy? Thanks!
Note added on August 23, 2021: Since I could not get any advice on the right size resistor to use I decided to try the same size that was advised for AA batteries: 10 ohms. It seems like this is providing good information but a word of warning to anyone else who might want to try this method. Li-ion batteries can put out a lot of watts, enough to overload many resistors. Make sure the resistor you use is able to handle the wattage that a Li-ion battery will generate.