Over the past two weeks, my MBP 16 inch would discharge its battery down to about 90% then recharges back to 100% all by itself, with the power adapter plugged in the whole time. It's happening roughly once a day at random hours. Anyone else running into the issues and/or has any advice on how to diagnose this issue?
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Macbook Pro 16 inch 2021 automatically discharges and recharges
- Thread starter haginile
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That's not an issue. That's battery health optimisation. It's doing this to maintain longevity of the battery because it would not be healthy for the battery to stay at 100% without getting a little exercise now and then.
Thanks I thought that might be what's happening, but my expectation – since the system is plugged in pretty much constantly – is for the machine to drop charge level to 80% and hold there. Instead, the machine is discharging to 90% only and immediately charging back up, increasing charge cycles. I've also disabled Optimized Battery Charging, so this behavior is little bewildering...
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Hm. I did think this would be tied to the optimised battery charging setting so that is a bit odd. Possibly a bug that it continues to do it even with the setting off.
I will say though that "keeping it at 80%" would also increase the cycle count because if you let it drop to 80% and then just run it off of the power adapter, the battery will still discharge naturally - slowly, but it will. And so to keep it at 80% it would need to throw power at it every now and then or a tiny bit continually. This might be better for the battery, but I think Apple also wants to reach a compromise of battery health optimisation and keeping it where you can pull it out the charger at any point and go out with it and not go "why is it at only 79%? I had it charging this whole time"
Thanks!
Reading Apple's support documents, it does appear that "Optimize Battery Charging" and "Battery Health Management" are two different things on Apple Silicon Macs. On M1, only the former can be disabled; On intel Macs, both can be disabled. So it's possible that it's indeed BHM doing its work. Still, I find it a little troubling that it's doing this on a daily basis...
I haven't seen this with mine plugged in nearly all the time. I have optimization on, so maybe that affects it.
On a side note, I've noticed that disconnecting power even for a split second causes the optimization to derail, so the battery recharges immediately to 100% and stays there for a day or two before going back down to 80%. I doubt it's supposed to do that, given my usage pattern. Or it's not very smart if it is supposed to.
On a side note, I've noticed that disconnecting power even for a split second causes the optimization to derail, so the battery recharges immediately to 100% and stays there for a day or two before going back down to 80%. I doubt it's supposed to do that, given my usage pattern. Or it's not very smart if it is supposed to.
There actually was a Macrumors article that confirms that battery health management can't be disabled on MBP. Perhaps this is BHM doing its thing after all..
There are two stages to battery health management. The first is the daily bounce between 80% to 100%. If the system determines that you indeed rarely use the battery, it will move to stage two. It will hold the charge around 70-80% and cycle once in while.
I believe the former refers to "optimized charging," where the system charges only to 80% and waits for the optimal time to charge to 100%, while the latter is "battery health management" where the system settles down at 70-80% and holds the charge there. Is that the correct understanding?
I feel the situation I'm in falls into neither category though.
I don’t believe so, although there’s no Apple Support documentation on any of this. Optimized battery charging wouldn’t discharge your battery at all. It only waits for the best time before charging to 100%.
Right now, you’re in the first stage as your MacBook isn’t sure if you’re always plugged in. So it continues to shallow cycle the battery. If you wait a few more days or weeks, it will determine that you rarely use battery. It will drop to 70% or 80% and hold it there without going back up.
it will drop to 80 percent eventually if plugged in for too long, at least with optimised charging left on. i have had my 14 do this and it stated when i checked the battery level that this was why.
what software are you using to monitor the drop?
does it start during hibernation/sleep?
I've had this problem for two days and it's driving me crazy.
The battery shouldn't drain itself while the mac is plugged in. I understand natural drain and battery optimization but this doesn't seem to be it.
does it start during hibernation/sleep?
I've had this problem for two days and it's driving me crazy.
The battery shouldn't drain itself while the mac is plugged in. I understand natural drain and battery optimization but this doesn't seem to be it.
what do you mean by daily bounce? That while plugged in it actually disconnects the power and runs the computer on the battery until it reaches 80%? that makes no sense.
I've had this problem for a few days and I've never seen this until now. coconut battery reports it's actually charging the battery with 5W (not sure it is actually doing so). There are a lot of reports like this and it's super weird.
I had the same thing with battery optimization enabled. It drops to 80%, holds it as long as I do not disconnect the charging cable. If I move to other room and connect to AC there it starts to charge it to 100% again, which is obviously stupid (as I disconnected for 1 min just to move to other room). It also starts to charge to 100% if it learned next day I might be using the battery. I don't think it is healthy, so I ended up installing Aldente Pro, disabled battery optimizations and now it works like it should (it keeps the charge at 80% whatever I do), no uncontrolled discharging and charging.
It makes complete sense if you understand that keeping a battery fully charged negatively battery health. This has been reported for this past year and half now.
so the solution is to let it discharge then immediately charge it again? It would make sense if it did drop at 80% and leave there. Then again that means the computer decides randomly to cut the power source I'm using without a modicum of explanation leaving me to believe my charger or outlet or cable is toast. That's a really ****** design. That also means the coconut application reports the charger is delivering power to the battery when it is in fact the battery that is powering my system. that also does not make sense.
macOS doesn't know yet if you're connected to power permanently or temporarily. This bounce is a compromise between battery health and battery power availability.
I already described the two stages of battery health management above.
optimized battery charging is described here;
https://support.apple.com/en-us/HT212049
supposedely this is what caps the charging to 80% based on usage (I've used this and it kind of works as advertised). I would expect that it doesn't recharge until you reach 80%; which means a natural drop in charge that occurs over weeks; not that it powers itself from the battery.
so the "bouncing" you describe is a different thing because it does seems the battery is powering the computer while plugged to the wall. Wether optimised charging and battery health management are two different things isn't clear either.
I never said anything about Optimized Battery Charging.
I've only talked about BHM. What you're seeing is BHM.
So BHM is also why the mac isn't immediately charging when I plug it and it's 50-60%? even
me right now trying to understand all of this
"wtf my macbook grew an arm and hit me in the back of the head?lol when first new MBP arrived to people, this forum was all about battery optimisation not working and why not, now looks like its doing something people are complaining againfull circle
-well that's perfectly normal that's how the battery health management works you silly"