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Still 100% charged after introduction of battery health management

Since the introduction of battery health management in macOS 10.15.5, I have seen people reporting battery charge reduced to something lower than 100% if their Mac is always plugged into the AC adapter. My 16inch MacBook pro is also always plugged into the 96 watt adapter, but the percentage is never reduced and is always 100%. However, I have observed periodic short discharge (about 15 minutes) and recharge cycle, and also observed reduction of full charge capacity (a.k.a. battery health) reported by coconutBattery (and iStat Menu) down to 92%.


I wonder why the battery health management on my MBP is not behaving like what other users reported. I'm trying to convince myself that my Mac is doing the battery health management by reducing the nominal full charge capacity while still showing 100% charged, but I'm now sure whether that's how battery health management is supposed to work.


I have tried manually discharging the battery to like 20% and plugging it into the power again, but it still did not stop charging until showing 100% charged.

MacBook Pro 16″, macOS 10.15

Posted on Jul 20, 2020 7:21 PM

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Posted on Jul 20, 2020 8:26 PM

buckeyes20 wrote:

However, I have observed periodic short discharge (about 15 minutes) and recharge cycle, and also observed reduction of full charge capacity (a.k.a. battery health) reported by coconutBattery (and iStat Menu) down to 92%.

This is the normal pattern with Battery Health Management. It allows your battery to remain at 100% but periodically (maybe once per day) executes a short discharge of 8-10% and then recharges back to 100%.

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Jul 20, 2020 8:26 PM in response to buckeyes20

buckeyes20 wrote:

However, I have observed periodic short discharge (about 15 minutes) and recharge cycle, and also observed reduction of full charge capacity (a.k.a. battery health) reported by coconutBattery (and iStat Menu) down to 92%.

This is the normal pattern with Battery Health Management. It allows your battery to remain at 100% but periodically (maybe once per day) executes a short discharge of 8-10% and then recharges back to 100%.

Jul 20, 2020 9:08 PM in response to buckeyes20

In looking at your table of battery health, I feel that it shows that there is some degree of "inaccuracy" in the estimate of battery health (full charge capacity). While it is true there appears to be a decline from 98% to 92% over a short time frame, notice that the "health" earlier declined from 100.7% (greater than 100% ?) down to 89% over just 10 days.


Here is a record I have for two laptops, one a 2010 Macbook Air, the other a new 2019 Macbook Pro. Note that the older Macbook Air has seemingly improved over the past 3 years! Is that physical? I seriously wonder if any of these readings are good to better than +/- 10%!




Jul 20, 2020 9:28 PM in response to steve626

The raw full-charge capacity read-outs are the same as the ones reported in System Report, so it is what it is. I guess all that the 3rd party softwares do is to pull the raw read-outs from the system and divide them by the design capacity.



By the way, as a new Mac user, I'm impressed by the battery health and longevity of your MacBook Air! Hope that my 16inch MBP can keep working for next 10 years. None of my previous Windows laptops (thinkpad, XPS) had kept working without any hardware issue for more than 3 years, except for the old Sony VAIOs ditched purely for performance reason. That is why I made the decision to give MBP a shot.

Jul 20, 2020 8:35 PM in response to buckeyes20

I am not an expert on this. But I have observed this on two Macbook Pro 16" laptops and it's very repeatable. I have also read anecdotally in the forums others' posts stating as such. In fact, at this moment, my laptop stop discharging when it reached 92%, while I was typing and just began to charge back up to 100%, as it seems to do every day at about this time ...

Still 100% charged after introduction of battery health management

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