Chosen Solution
As noted here iMac Intel 21.5" Retina 4K Display 2017 Teardown picture 10, does the 2017 27" 5K iMac have a lithium CMOS battery? I am guessing yes, but I wait for the experts. Thanks!
That’s the 21.5" teardown, we don’t have the new 27" model but if you watch the OWC vid here you’ll get a glimpse of it - teardown of the 2017 27-inch Apple iMac. I’ve pasted an image of the previous model which is exactly the same above.
