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The March 2015 update of Apple's 13" MacBook Pro Retina Display, model A1502, features fifth-generation Intel Core i5 and i7 processors and introduces the Force Touch trackpad.

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Random Shutdowns When Battery Is Low

So I replaced my A1502 battery a couple of weeks ago and everything seems to be working smoothly. However, when the battery drains to about 4%, the machine abruptly shuts down. When I press the power button, instead of the laptop recognizing the battery is low and flashing the battery low symbol, it tries to boot and shuts down about halfway through the progress bar. This is a new problem for me. I have tried resetting the SMC, PRAM, and tried numerous battery calibrations. Is this intended behavior, or is my unit defective? Should I worry about battery health going forward?

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Edit: added coconutBattery screenshot

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Here is a screenshot of coconutBattery while charging from 0%

Update (06/14/2022)

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Here is a screenshot after over 10 hours of uninterrupted continuous charge. Something to note is that the machine occasionally gets choppy on low battery which may be a power output thing.

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Edit: screenshot from when throttling starts to occur.

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16 Comments:

Let’s get a better view of things, install this gem of an app! CoconutBattery take a snapshot of the apps main window and post it here for us to see Adding images to an existing question

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After resetting the smc and PRAM, the current charge reading on coconutBattery changed from 99.9% to 98% while the system still displayed 100%. Keep in mind I’ve left it charging and left it on with a green light for 7 hours.

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OK Good! Now disconnect the MagSafe and let it run down until it shuts off while being used. We want to find that point, and once it goes into sleep mode, you'll want to plug in the magSafe give it a minute or so and take another snapshot. Once we have that we should know what's up.

Now one piece of info we also need along with the battery cutoff is the time it took to get to that point and what was the running load using Activity Monitor to watch and capture the load and battery usage. Review this View energy consumption in Activity Monitor on Mac copy the graph and past it in as well

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I usually only browse the web on it so the load isn’t high so I get anywhere from around 7 to 8 hours (although the os estimates there is around 9 hours).

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@Troy - Thats about right, so I'm confused?? Your system then is working correctly. Your system will go into Sleep and then deep sleep when the battery gets low and that's about when it will happen.

The way you implied it was happening sooner, which would be a bad cell or the battery was not calibrated. Basically SMC needs to reset its high and low thresholds.

Resetting SMC clears them and running the system until it has gone into sleep sets the low bar and then the next charge fully (a full 15 hours) will set the high and doing it a second time. Any deviation of this will set it for that window and over time the window will increase from use as it learns.

Basically, the one time set or inching its way over multiple times of charge and discharge.

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OK, Now let's plug in the MagSafe give it a few minutes and take a fresh snapshot so we can see it under charge. If its charging give it a good 10 hours turned off, then take one more snapshot.

Let's see how it charges and if it gets to a full charge. I'm thinking we may need to do a hard SMC reset. But I want to be sure before we go through the process.

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Ok, I edited the post. The capacity of the battery is reported as 7046 mAh. So this would lead me to believe that this is almost certainly a calibration issue. I have power cycled the machine numerous times and hard resetted the SMC/PRAM.

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Batteries can trip off even with good capacity data. Capacity and peak power output are different parameters and mostly independent from each other.

You most likely got a battery that has adequate capacity but only works on low output, during high output, high internal resistance causes the output voltage to drop sharply and the computer just trips off.

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@tomchai - I've found one cell could be bad which mis-leads! But we need to work it from a full battery to be sure.

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@danj Could be the problem, battery packs with cells connected in series always suffer from this problem, one dead cell and the whole pack underperforms.

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Troy will be eternally grateful.
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