To calculate the battery capacity in mAh of an 18650 battery I understand you can use something like an iMax B6 in discharge mode on a fully charged (4.2V) battery to get the mAh it provides. The iMax B6 stops at 3V.
So my understanding of this is that the reading shown is the mAh that were provided by the battery going from 4.2V (or whatever it charged to) down to 3V.
I understand that running an 18650 Lithium Ion battery below 3V causes chemical instability and shouldn't be done. So what I am unsure on is if the value shown on the iMax B6 is the "rated capacity" for this batteries (the ones shown on the specs and printed on some batteries) or if you need to do some other calculation to get the full capacity of the battery going down to 0V?