Macbook 12" battery dead after 386 cycles

If you click the Apple, click About this Mac, click System Report, click Power, and look for Full Charge Capacity. The original capacity is ~5300 mAh. I suspect yours is less than 80%.

Have similar config as yours except is Refurbished from Apple and 2016 model. Bought in April 2017. Now have 44 battery cycles and 95% of max life. You mention "The battery side is probably a little bit inflated so the case doesn't fit together as on another side. Look like the battery gets bigger somehow."

Strongly suggest you get it looked at by Apple. Signs of defective battery

My early 2016 Macbook threw a service battery warning at 18 months and 171 cycle counts (<80% full charge capacity). The Genuius Bar told me I would have to pay $199 for a replacement. I'm now at 227 cycle counts and 51% full charge capacity. Scanning the forums, battery issues and battery life in general with 12" Macbooks is a problem.

Perhaps this article "About Mac notebook batteries" can be of some help.

Specifically : "Your Apple One Year Limited Warranty includes replacement coverage for a defective battery. If you purchased an AppleCare Protection Plan for your Mac notebook, Apple will replace the notebook battery at no charge if it retains less than 80 percent of its original capacity. If you don't have coverage, you can have the battery replaced for a fee."

I just checked my battery cycles trying to figure what may be causing the weird shutdown behavior I noticed recently with my MacBook 12" early 2015. I had a service battery alert showing, with the number of cycles showing only 203. I use it mostly plugged in to the charger. It says it is pretty much at maximum capacity. Why would it show the need for service?

Ok, if that is so, it looks like i have only 68% when fully charged. 😟