Well you're the Engineer, but I guess we will just have to agree to disagree here because it says right on the side of the cell that it is a ICR18650 - which means it is either a LiCo cell or the batteries are intentionally mislabeled to throw people like me off.
Or are you considering the protection circuit to be a non-standard addition to the cell?
EDIT: I just wanted to add that I really appreciate your presence here and in no way am I trying to be snarky or rude to you. I'm just trying to understand the situation here.
Well I mean I'm sure a techie could replace it... but that really isn't the point. YOU should be able to replace it in a perfect world!
Since you asked nice
You are right, it is an 18650 Li-Ion cell, and is not mislabeled.
However, during R&D we found a problem with the standard 18650 cells. The discharge rating was not sufficient to power the Pinnacle
reliably. This goes into some really technical aspects of how batteries work, but to simplify we had issues with the battery voltage dipping below "critical" voltage and resetting the electronics. That's bad.
We had to tweak the battery chemistry to allow higher discharge rates. This results in the rating being lower, but the system being stable.
A point of interest; for those that care: Just because a battery is rated at 2600 mAh vs 2200 mAh does not mean it has higher capacity. ( I know, seems backwards right?) This is because the rating is usually at a slow discharge rate, say 300mA. Heaters, take a TON of energy, so the pull way more than the rated discharge. Depending on battery build and chemistry this causes problems. We actually get better run times off a 2200 mAh battery than a 2600 mAh battery.