Looking to try and narrow down the root cause of cranking issue of 2014 Mini Cooper S with 102k miles, original owner and only services at BMW so far.

• The battery is 3 years old and was bought and installed at the BMW service center.
• Bimmercode says the battery has 87% charge after interstate drives ( 20-30 miles) and 83% after short in town drives (3-5 miles).
  • Volts when driving on interstate 13.8 to 14.4
• Have never manually charged the battery or jump started
• The starter is the original from 2014.
• No recent changes or service to the car in past year, this issue started about a month ago around 98k miles

Events,
When hitting the button to start the car, it randomly has issue trying to turn over and crank.

• Sometimes turns over and cranks normally without issue.
• Sometimes tries to turnover and crank, but power seems very weak to turn over the starter and all then instruments and lights go completely off (even have to reset the clock) and it fails to start.
  • If i hit the start button again right after this failed start, it seems to always turn over and crank to full start up.

BMW says needs new battery and starter, i don't mind if this is what it needs. but i for the first time find I am looking for more feedback from others on recommendations or more questions i can help answer.

appreciate any feedback, Thanks!