mid 2015 MacBook Pro battery recall & calibration of new battery

No need. You are good to go.

About Mac notebook batteries - Apple Support

https://support.apple.com/en-us/HT204054

Determine battery cycle count for Mac notebooks - Apple Support

https://support.apple.com/en-us/HT201585

Batteries - Maximizing Performance - Apple

https://www.apple.com/batteries/maximizing-performance/


Nosmadab wrote:

Thanks. I was hoping that would be the answer. I want to give the MacBook credit for being 'smart'!

If you use it occasionally on battery power alone it should be fine. Battery management has gotten a lot better over the years. Certainly there’s no need to do a full charge and drain, which used to be Apple’s recommendation before the current 1000 cycle batteries.

Nosmadab wrote:

My tech savvy 37 y.o. son always wants to err on the side of built-in Mac smarts. As the old, cautious, doubtful dad, I need confirmation from my 'support group'. Thanks!

Well, you need to go into all this with an understanding that “battery health” and “state of charge” are always just an estimate. It’s been a long time since dumb lithium rechargeable batteries were charged similarly to NiCads or NiMH batteries solely based on monitoring batter characteristics. I remember when state of charge was just a battery symbol that’s solid, a low charge warning, a flashing low charge warning, and auto shutdown. That’s when batteries caught on fire often and a lithium-ion battery might be rated for 200 charge discharge cycles.

These days the battery management is smarter and estimated state of the battery is stored in a control unit on the battery. That’s great unless it gets corrupted (I saw negative capacity on a MacBook battery once). However, it’s all still an estimate. It’s impossible to know how much charge is in a battery (like fuel in a liquid tank) so it has to be estimated based on monitoring. And once upon a time the whole thing about calibration made sense because “Coulomb counting” worked well. Charging and draining still gives an excellent idea how much capacity there is, but now the tech is better and it’s not strictly necessary.

Nosmadab wrote:

With every reply to my question I'm learning something new. I'll admit I had to look up Coulomb counting, but it's very interesting, even if I don't fully understand it. I appreciate your insights!

I don't fully understand all the ways that battery health and state of charge are calculated. There are entire doctoral dissertations on it and numerous technical papers. And some of the math is beyond my limited comprehension. As an engineer, I'm a 0s and 1s guy.

However, Coulomb counting is conceptually very simple. Just figure out how much charge/energy goes through the battery from "full" to "empty" and use that to to determine how much is in the "fuel tank". That was the idea behind battery calibration - to get a better estimate of how much energy is available when fully charged by calculating the amount of charge a battery goes through in its entire usable range. It's like an electric meter calculating how much energy has been used in a house. Theoretically monitoring partial discharges can do some of the same things, and I suppose the technology is so much better in using that amount of information to determine the health of the battery.