Chosen Solution

I realize this MacBook Pro is bordering on obsolete being a 9 year old model, but I’ve been very happy with the machine and don’t feel the need to upgrade for a bit longer. However, my battery is beginning to show its age. How much longer does it look like I have on this rMBP before it is time for a battery? I bought the machine used as a buffer between the 2012 13" aging, and the 2016-2019 Butterfly and USB-C only disaster machines, so I don’t know how well it was cared for between me and the 1st (as well as a likely 2nd) owners. The difference at the time was minor, but both the 2014/15 are about the same in terms of age.

Turns out it may be more due then I though :-(. Loses 2%/charge.

You can replace it if you want, you still have a couple of years of OS compatibility before you drop off the update bandwagon. You can of course use it for longer, though you’ll have to use Firefox or some other still-updated browser for security reasons. And you’ll want to exercise more caution in general. But your battery has time on the clock, but not a lot of miles. You’ve been good to it. If it were mine, I would wait. I’d hate to replace my 87% battery and get an expensive failure a few months later. Lithium batteries have five enemies:

Time. Nothing you can do about this.

Cycles. Yours are low. My MacBook pros have always been used as desktops, so they have low cycle count. Keeping it connected to the charger reduces cycles, but can lead to problem 3:High voltage. Battery degradation is accelerated while voltage is high. Fortunately, Apple has moved to adaptive charging, which notices that you’re a desktop guy, and stops charging before the cell voltages get too high (at about 80%). Most or all modern laptops do this, though sometimes it is manual, not automatic.High temperature. Don’t leave your MacBook in a hot car.Low voltage. Really low, less than 2 volts/cell. You can’t run the cells down this low, the battery management system shuts you down long before then. What you can do is discharge to shutdown, then put it on a shelf for several months, where self-discharge will do it for you. This is not degradation. This is death. Once the cells get that low, they are unsafe to charge, so your battery management IC kills the pack.

You have two things coming at you age and cycles! The age of your battery is now over seven years old (2015 - 2022) for a battery which lifespan is about five years. The cycle count is 233 currently, this battery has an expected cycle of 1,000 cycles (+/- 10 %) Determine battery cycle count for Mac notebooks So I would say its already on borrowed time! Time for a fresh battery. You should be able to get at least 5 more years if you give it the needed TLC.