Why is my 2011 MacBook Battery dying so quickly?

I do have the original battery, I will put it back in and tell you what happens.

just put the old battery back in, on coconut battery status says check battery has 830 cycles but the computer still works. It is losing charge around the same rate as the new one. it is at 13% and activity monitor says it will die in 12 minutes.

Also it says discharging with 23 watts, a minute ago it said 30 watts. The newer battery was reading around discharging with 8-10 watts. I don't know if this means anything but its something I noticed.

Nevermind I think that is normal

@jude85858 - Okay, your original battery is draining at the same rate as the replacement. Here's the action to take:

Quit any apps that you are not using and let the battery drain slowly. Set the screen to never sleep in the energy saver pane in System Settings (System Preferences), and disable the screen saver. Once it drains, then vigorously calibrate it (that's just what I call it). Charge it to 100% WITHOUT ANY PROGRAMS RUNNING, and leave it plugged in for 2 hours. Then, try playing 4K / HDR / 60 FPS videos. You can find these on YouTube without too many problems. Play this until your Mac shuts down. Do not let the videos stop playing. (To make this process even more accurate, try running many applications at the same time. Open Photo Booth to operate the camera. Keep the Activity Monitor update frequency at very often. This will drain the battery very quickly. Then, leave it drained overnight, and charge it to 100% WITHOUT INTERRUPTION.

thank you I will try this and tell you if it does anything.

@jude85858 Have it charged up as much as possible before doing it :)

@jude85858 & @livfe - Just so you guys know, com.apple.power files are so macOS understands battery information, power adapter information, etc. I wouldn't think that these files could be draining the battery, but it definitely is possible! I would recommended that you have a backup of these files before removing them, or else your Mac may crash at sleep, have an X on the battery in the menu bar, etc. Also, macOS will not like it if you are messing with the system files, so you'll probably have to turn off System Integrity Protection before you proceed. If something goes horribly wrong, it may cause you to reinstall macOS. Good luck!

@jadonlyon No need to disable the system integrity, they just fly to the bin!

On a reboot they appear to be freshly created by the system, I never had a problem doing it so far and it did seem to correct some 75% of SR's on batteries. So a new battery and these 'new files' I would think help the system to have only the info regarding the new battery in case they did carry over any previous info from an old battery. Worth a try at least.

@livfe - Definitely worth a try! You are absolutely right!