iPhone 4S Battery
Took an hour because I was taking my time and blew out all the nasty dust that permeated the entire inside of the nearly 4 year old iMac. Used an AdaptaDrive with an OWC thermal sensor, and a Samsung 850 EVO 1TB. Unscrewed the pins on the drive and the bracket on top and attached that hardware to the AdaptaDrive frame. Cloned the drive ahead of time and when powered up, the thing screamed to the desktop. Fans are both sitting at ~1150 RPM. So, success!