My old 2012 MacBook air suddenly shut down. I had the battery recently replaced by a non-Apple shop since Apple has already obsoleted this model.
The battery was somewhere between 60% and 80% when this happened. I wasn't doing anything particularly power-consuming, WiFi was on but I was just editing some slides (no active browsing or movie-watching).
I plugged the power in and restarted. The date was reset to something in 2018 and the time was wrong. I connected to the internet and let it auto-reset.
I've had this new battery a month or two and it's worked fine until today; I can work offline for ~5 hours and still have ~30% charge left.
Question: I've never looked closely at the console reports before so I don't know how to search for a sudden shut down, possibly due to loss of power. I do know that I had to reset the clock after starting again. How can I zero in on "something bad happened" reports?
Battery Information:
Model Information:
Serial Number: W0137xxxxxxxx
Manufacturer: SMP
Device Name: BQ20Z451
Pack Lot Code: 0
PCB Lot Code: 0
Firmware Version: 201
Hardware Revision: 000a
Cell Revision: 158
Charge Information:
Charge Remaining (mAh): 7596
Fully Charged: No
Charging: Yes
Full Charge Capacity (mAh): 7845
Health Information:
Cycle Count: 31
Condition: Normal
Battery Installed: Yes
Amperage (mA): 333
Voltage (mV): 8362
Best Answer
You can get the previous shutdown cause from the log history.
In macOS Sierra and later with unified logging:
Earlier than macOS Sierra, filer system.log for some recent results:
Then look up the code on this table I maintain: Previous Shutdown Causes Explained