Battery service and insanely low maximum charge

Recently my Macbook Pro Retina Late 2013 has started to shut down unexpectedly while running on battery. I thought it was because of my CPU was too hot but it was not the case. When checking it further, I found that my battery status is "Service Battery". I used coconutBattery to check and found that the Full Charge Capacity of my Mac is insanely low. I could be sure that it was around 90% last week and suddenly now it dropped to 46.9% of the Design Capacity.

I tried resetting SMC like many other said but unfortunately, it did not work for me. One symptom I saw before having this issue is that my Macbook temperature was quite high. I could feel the obvious difference in temperature between my Macbook and others' at the office when touching my hand on it, I guess my Mac was about 10 degree Celsius higher than others.

Is anyone here had this issue before? Should I replace my battery completely? Is it possible to replace the battery only on this Mac, I think it is nonremovable?

You need a new battery.

This is confirmed with the following two conditions as stated in the question:

• When checking it further, I found that my battery status is "Service Battery"

• I used coconutBattery to check and found that the Full Charge Capacity of my Mac is insanely low

Your battery, according to it's manufacture date, is over 3 years old, so it's not out of the norm for it to begin failing at this time.

Replacement batteries are fairly inexpensive and fairly simple to replace ("simple" as in not a complex procedure), but it's considered "difficult" because it's glued into position so it requires diligence to remove. ifixit.com has an excellent step by step guide if you want to tackle this yourself.

The Service Battery state means that the battery is malfunctioning. This would explain the abrupt full charge capacity decrease, as there could be faulty sensors in the battery. Although it still can be technically used, you should replace the battery ASAP.