@matigo Since the arrival of iOS 9, the problem is cured. Just hasn't happened at all.
Since this newer MBA has double the capacity of the MBP (512 GB vs 256 GB), I've spent the last 90 minutes copying my iTunes media files from the Pro to the Air as well as downloading 75 iOS updates. This was done withe the MBP in target disk mode, connected via Thunderbolt to the MBA.
@matigo iFixit.com is the answer, for example, here's the instructions for swapping out the battery in this 2014 MacBook Air 11-inch: https://www.ifixit.com/Guide/MacBook+Air+11-Inch+Early+2014+Battery+Replacement/24735 Very straightforward.
// @skematica
@variablepulserate 2011 is quad-core MacBook Pro with dedicated graphics card & 12 GB of RAM. 2014 is dual-core, lower-clocked MacBook Air with 8 GB of RAM & integrated graphics.
// @matigo
Seems I may have tracked down the former user of this ex-Apple MBA: She's an Enterprise Business Development Manager in Sydney, Australia. Her name was on a sticker on the base of the computer and it was showing as paired to her Magic Mouse.
The faster read/write speeds are for the 2014 MBA vs the 2011 MBP.Fired up the old MBA under Recovery drive & erased the SSD, then downloaded a new version of El Crapitan to do clean install on it. Took about four hours all up. Only one update required, that being RAW camera compatibility.
Brake fluid is a subtle chemical to attack other vehicles' paintwork, it softens the paint slowly & insidiously. PVC conduit cement is far more violent. In 30 minutes it can bubble a painted surface back to the base metal.
// @matigo