MacBook turning off suddenly
Your MacBook Pro battery has a life expectancy at or around 1,000 cycles.  It's not uncommon for batteries to exceed or fall short of this number; as every user is different in terms of what they use their computers for and how/when they're using AC power etc. So the 1,000 cycles is just an estimation of how long it can last. At 658 cycles it's more than likely that your battery is still okay, but it's also not unheard of that it could be on its way out.

If I was you I'd try resetting the SMC.

Reset the SMC

To reset the System management Controller on your particular MBP, follow these steps:


Shut down your computer
Keep the power cable plugged in
Press at the same time shiftoptioncontrol (on the left side of the keyboard) and the power button and hold all these down for at least 10 seconds
Let go
Turn your computer back on with the power button.


Now use your computer to determine if the issue still persists. If it does you could run Apple Hardware Test.

Running Apple Hardware Test

Your model MBP uses Apple Hardware Test to test its hardware. You can do this as follows:


Fully shut down your MBP
Disconnect any external hardware connected to your MBP1
Restart your MBP
Immediately press the D key and keep it down until you see the Apple Hardware Test icon appear
When prompted, select your language and click on the right arrow
When the AHT console appears, you can choose to run Basic tests by clicking the Test button. However, I suggest you select the "Perform extended testing" checkbox before you click the Test button.
Your test results will appear in the window in the bottom-right of the console.


Note 1: that the extended test will take some time. Take a note of the results and report back. 

Note 2: If pressing and holding the D key at Step 3 doesn't work, start again at Step 1 and, at Step 3 press and hold both the OptionD keys instead. This will try and run diagnostics from the internet instead, so you will need to allow more time for it to complete. Be aware that if you connect to the internet via an ethernet cable instead of Wi-Fi, then keep this cable plugged in during the process.

1 If you need to use an external keyboard, mouse or display you can keep these connected. However, if you don't need to, then test your MBP without these being connected.