Hi why my MacBook Pro don't show low battery alert when 20%?

A low battery alert won't appear until it's below 5%. If you think it's misbehaving perform an SMC reset.

What are you asking?

OK, to perform the SMC reset follow these instructions. Read all the steps.

Before Resetting the SMC

Try each of the following steps in this order before you reset the SMC. Test the issue after completing each troubleshooting step to determine if the issue still occurs.

1. Press Command + Option + Escape to force quit any application that is not responding.
2. Put your Mac to sleep by choosing the Apple () menu from the upper-left menu bar and then choosing Sleep. Wake the computer after it has gone to sleep.
3. Restart your Mac by choosing the Apple () menu from the upper-left menu bar and then choosing Restart.
4. Shut down your Mac by choosing the Apple () menu from the upper-left menu bar and then choosing Shut Down.

Resetting the SMC on Mac portables with a battery you can remove

1. Shut down the computer.
2. Disconnect the MagSafe power adapter from the computer, if it's connected.
3. Remove the battery (to remove the battery - click here: MacBook or MacBook Pro).
4. Press and hold the power button for 5 seconds.
5. Release the power button.
6. Reconnect the battery and MagSafe power adapter.
7. Press the power button to turn on the computer.

Still having problems? Replace steps 6 and 7 with the following:

1. Reconnect just the MagSafe power adapter.
2. Press the power button to turn on the computer,
3. Then reconnect the battery.

Resetting the SMC on portables with a battery you should not remove on your own

1. Shut down the computer.
2. Plug in the MagSafe power adapter to a power source, connecting it to the Mac if it's not already connected.
3. On the built-in keyboard, press the (left side) Shift-Control-Option keys and the power button at the same time. The power adapter indicator light will cycle off / on once.
4. Release all the keys and the power button at the same time.
5. Press the power button to turn on the computer.

Hi John, How do I get rid of the "service battery" warning?

I did the SMC reset as you suggested (twice) but it still shows.

I have also noticed that the "low battery" alert doesnt appear anymore when my battery reaches 5% or lower.

My laptop just shuts down.

Please help. I have a 2013 MBP 13" with Retina display and running Mavericks OS X 10.9.5