115      iPhone_iPad_Mac_apple

Battery Cycles not increasing when charging

Hey,

I just noticed something on my MBP (2013, 15'' retina) and wasn't too sure about why this happens:

I use the MBP as my main computer, which mains when I'm at home I always plug it in. This also means that, for example on weekends, it's plugged in for multiple days in a row. Now I noticed this: When my battery is 100% and I keep the MBP plugged it, the cycle count never increases. As far as I know, my old MB (air) didn't behave that way. With my old MB, when the battery reached 100%, it would discharge to about 95% then start charging again, slowly increasing my cycle count. The new MBP always shows 100% battery and the current power usage - read out via the IOKit API apple provides - shows 0 mAh.

Does anyone know if the new MBP is actually "bypassing" the battery when plugged in and at 100%? Or is the cycle count basically wrong?

I think your question is not getting answered.  So here it is:  When plugged in, the MacBook Pro draws power from the external supply.  See this link for information on battery care:

https://www.apple.com/batteries/notebooks.html

Hi n,

Even if the batt was being "bypassed," it would slowly lose its charge.

The cycle count is based on full cycles, even if they're not all at once. For example, if you used 20% of a charge, and did that five different times, that would equal 100% and count as one cycle.

Hi, thanks for the response.

of course the battery would still lose charge, but it would be much healthier as if the battery was actually being used the entire time, wouldn't it? Especially for people like me who use their MB a lot when it is plugged in.

My point is that the cycle count is not moving AT ALL when plugged in. And, if I remember correctly, my old MB behaved differently. So I was just interested in if that is actually a change apple made with how the battery is used or if it's just a software thing (effectively making the cycle count much lower thant it should be).

The battery counts a cycles when it has counted a certain threshold of charge.  This means that if you discharge the battery part of the way down then charge the cycle count will not increase until a later charge.

Said another way...

the cycle count increases when the battery accumulates a certain amount of charge.  Let's say that threshold is 1000mA-Hr.  If you discharge the battery 500mA-Hr, then connect the charger the gas gauge IC will end up counting 500 mA-Hr.  You will have to charge another 500 mA-Hr before it counts.

The net effect of this is that your cycle count will stay low IF you run on the charger most of the time becuase there will be little discharge.

Finally... Apple buys the gas gauge IC from companies like Texas Instruments (TI).  Apple does not define this behavior.

thanks for the explanation. until now I assumed that the battery would be discharged for the same amount of energy when plugged in and when not plugged in. your last sentence makes me think this is wrong? so are you saying that the battery is used less when plugged in (which is what I meant in my initial post when I talked about "bypassing" the battery)?

nachdenki wrote:

My point is that the cycle count is not moving AT ALL when plugged in. And, if I remember correctly, my old MB behaved differently. So I was just interested in if that is actually a change apple made with how the battery is used or if it's just a software thing (effectively making the cycle count much lower thant it should be).

See my previous post. If you leave it plugged in, it would take 20 times going from 100% down to 95%, then charging back up to 100%, and repeating, until it would count as one cycle. That would take quite a while.

I think your question is not getting answered.  So here it is:  When plugged in, the MacBook Pro draws power from the external supply.  See this link for information on battery care:

https://www.apple.com/batteries/notebooks.html

Thanks.  We gamers/powerusers care deeply about this sort of thing... especially since Apple made user-replaceable batteries a relic of the past.

最後更新：2017-08-23 23:31:21

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