Why Macbook Pro 13" 2017 Charges Faster?

[Sovon Halder]

I use iStatMenus which shows estimated time for charging/discharging. But each time I plug in the power adapter, the laptop charges faster than the estimated time. For e.g.

If I take a reading of 1 hour 42 minutes to full charge at 12:37, it should complete at 2:19.

But it completes in 1 hour 7 minutes.

NOTE: Before taking the reading I've waited about 10 minutes for the estimate timer to settle down. And there hasn't been any workload difference during the charge period and the system charged at full 60W power draw directly from the adapter.

I understand that these numbers are estimates based on current activity and aren't meant to serve as a strict time guide but still, should there be this much of a difference?

 

[jerryk]

It is all a function of your usage. I bet if you start doing something heavy like math computations or a lot of disk access the completion times will get longer. And if don't do anything and decrease the brightness the times will get quicker.

It's just like when you drive your car up a hill or down a hill, your mileage varies.

 

[Sovon Halder]

Yeah right. It’s supposedly to work that way. But I’ve been seeing this for a while and I mentioned that there hasn't been any workload difference during the charge period.

 

[FrozenDarkness]

Also, it's based on two levels of estimation. It's an estimation based off your usage, but your battery level AND what 100% is are both estimations by the computer. sometimes computers will recalibrate what 100% means.

 

[evec]

The System will regulated down from power supply 20V to battery voltage (around 12-13V) and delivery both to battery charger and system usage, the system have first priority of using the power, and charger second.

When the battery level below about 75%, the battery can change it as much as power supply can be supply when temperature permit, which mean charging power = Power Supply - System Usage, the charging rate will floating based on your system usage, so why the indicate is not reliability, when the battery level about 75%，need require precision control of both current and voltage to avoid overcharge and damaged the battery, so the battery charge rate will reduce and reduce and the power supply don't fully utilized.

Also for Mac, the system show 100% not mean that it will be 100% fully changed, normally system will show charged when real battery level between 95%-100% and may need additional one hours to react 100% in accuracy.
It is because the battery will not recharge unless drop down to above 95% for battery life, and Apple show 100% for avoid confusion of normal user.

 

[Sovon Halder]

Right, I've seen the same behaviour while charging.

The first 60-70%, the battery gets charged really fast and then it somewhat slows down as it reaches 80-90%. What I find weird is that... there is this much difference between estimate and reality.

If this is the pattern, then the applications taking the reading should also be programmed that way, no? So it represents a more accurate estimation.
[doublepost=1513417002][/doublepost]Hah.. found something interesting that I didn't know about. Now I see even though the menubar shows 100%, it's not actually 'fully charged'. Also I can see that the voltage increases very very slightly but the amperage drops quite a bit.