I have an early 2015 Macbook Pro running Big Sur. It's displaying a "Battery service recommended" notification since recently

I checked the system information. Cycle count is 437 and full charge capacity is 4770 mAh. That seems odd, since Apple estimates the warning to come up after some 1000 cycles.

I looked in preferences to see if I had checked "Optimised battery charging" but the option is missing (Preferences > Battery > Battery).

I wouldn't be bothered much since this macbook is not my daily workstation and I wouldn't mind even if it had to run on the power adapter all the time. But I'm reading about how MacOS reduces the maximum processor speed by half when the battery has this status. I've noticed how it's slower than it used to be (but I can't really tell how much of the difference is between my ears due to p[acebo/suggestion to be honest).

I can't find much information about it, but I'm interested to know whether the reduction of cpu power is just happening while on battery or also when on AC power.

  • Feel free to show your research or cite who is saying this happens. I can edit my answer, but we’ve postponed maintenance on a good several dozen Macs while we get ready for a big M1 purchase at work. None of the dozen are measurably slower, including my daily driver MacBook Pro.
    – bmike
    Commented Jun 25, 2021 at 20:03

1 Answer 1


In my experience, speed is not reduced when service battery warning starts.

Only when the battery is disconnected (physically or the system disconnects it) do you suffer any speed reduction (and in many cases - it's not a reduction that is evident except for benchmarks).

The service battery is a warning to plan for service and not a "pull over and stop using the computer immediately" type warning.

Of course, all manner of other issues could happen at the same time so I would benchmark what you care about and then decide to spend for service when you are losing more money than it costs for the repair.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .