Target machine: MacBook Air, 13-inch, early 2014, MacOS Sierra 10.12.6, used for 4 years very carefully without any problems.
Battery has only 70 cycles, condition reported as "Normal", and still works good on long flights.
However, yesterday I faced a problem, when the battery was about 50%, system just performed hard shutdown. I tried to turn it on twice, it kept shutting down after 2-3 seconds after the system boot. After plugging in power it works without any problems.
I doubt if I can reproduce the problem, it means I should work from the battery in the moment of shutdown (and lose work results)
Does anyone met the problem? How to detect the reason, is it hardware or software, or just system settings (I believe, it should be warning and regular shut down, never drained the battery before)?