MBP randomly shuts down without warning

Question

Lately my MBP has been randomly shutting down when not plugged in to charger.
No warning, battery isn't low (usually about 50% charge), and the machine just turns off completely and won't turn back on until I plug it back in.

Answer 1

Here's what that shows (not sure what to look for):
Battery Information:
Model Information:
Serial Number: SMP-bq20z951-394e-1382
Manufacturer: SMP
Device name: bq20z951
Pack Lot Code: 0000
PCB Lot Code: 0000
Firmware Version: 002a
Hardware Revision: 000a
Cell Revision: 0100
Charge Information:
Charge remaining (mAh): 2720
Fully charged: No
Charging: Yes
Full charge capacity (mAh): 4208
Health Information:
Cycle count: 26
Condition: Good
Battery Installed: Yes
Amperage (mA): 1210
Voltage (mV): 11950
System Power Settings:
AC Power:
System Sleep Timer (Minutes): 10
Disk Sleep Timer (Minutes): 10
Display Sleep Timer (Minutes): 30
Automatic Restart On Power Loss: No
Wake On AC Change: No
Wake On Clamshell Open: Yes
Wake On LAN: Yes
Display Sleep Uses Dim: Yes
GPUSwitch: 2
Battery Power:
System Sleep Timer (Minutes): 10
Disk Sleep Timer (Minutes): 10
Display Sleep Timer (Minutes): 2
Wake On AC Change: No
Wake On Clamshell Open: Yes
Display Sleep Uses Dim: Yes
GPUSwitch: 2
Reduce Brightness: Yes
Hardware Configuration:
UPS Installed: No
AC Charger Information:
Connected: Yes
Charging: Yes