Finally, I figured out why one of my three batteries is awesome and the other two are not

[orca.skynet]

It would appear that the Q2 2018 Air batteries are the problem. The 2018.07 and 2018.08 Production Dates of M2 batteries are also prone to swelling. Any batteries produced after that seem to be fine.

We will see because my batt #0 only went through 14 cycles. Not sure which cycle I started seeing swelling for the others. I remember they didn't swell immediately.

 

[GadgetGuy]

We will see because my batt #0 only went through 14 cycles. Not sure which cycle I started seeing swelling for the others. I remember they didn't swell immediately.

Yes, that is the other possibility. The newer produced batteries haven't reached the same age as the earlier produced batteries to eliminate age as the cause, although on the swollen M2 batteries, it occurred well within 12 months, which would include batteries with Production Dates of 2018.09 and 2018.10 which haven't been known to swell yet. Time will tell all!