Chosen Solution
After installing a replacement battery (purchased from iFixit), my mid 2010 MacBook Pro consistently shuts down (without warning, like unplugging a desktop computer from the wall) when the charge level gets to about 30%. It also doesn’t seem to hold a charge any longer than the 7+ year old original part. Are there software settings that need to be reset after installing a new battery, or is this likely a faulty replacement part that I should get exchanged?
First try resetting the SMC.
