Battery percentage wrong and randomly dying

cjod wrote:

Since new, my laptop has been shutting down before it reaches 0%. I first noticed this issue when I went on vacation and left my laptop at home. When I returned home, I pressed the power button and nothing happened. I had to plug it in to get it to power up.

When I first plugged it in, the light on the charger lit up amber for a second and then went off. I then pressed the power button and the amber light came back on. When the laptop started the time and date were wrong (Midnight on April 1st) and they didn't update until I logged in.

I brought it to the Apple Store while it was under warranty and the technician told me to try a software update. I didn't think much of it because I rarely let the battery get below 10%, usually operating between 20 and 80%.

Now that my laptop is a couple of years old this has become a real issue. It will randomly shut off anywhere below 30% and when I plug it in and it comes back on the battery level will be much higher than when it died, like 50% and above.

I have tried doing full cycles to reset and also tried resetting the SMC and PRAM and nothing. When I charge it full it takes a very long time to go from 99% to 100% and then when it is at 100% it can stay there for a long time while on battery power. Something is clearly very wrong.

I have always used the original MagSafe and 61W power adapter. Coconut battery reports 249 cycles, 5,833mAh full capacity from designed 6,075 and battery health of 96%.

What can I do?

Base 2022 14" MBP M2 Pro, purchased new from apple in June 2023.

A SafeBoot Start up your Mac in safe mode - Apple Support will sort many anomalies

Reboot as normal and test.

verify your software is up to date—

The current stable release of Tahoe including bug fixes, security updates is macOS 26.1

Keep your Mac up to date - Apple Support

To be proactive you can file a bug report / submit your Apple Feedback here: Product Feedback - Apple

no resolve take it in—

In or out of warranty you can get a free over the counter 'Apple Service Diagnostics' test /assessment

Make an appointment for a "hardware issue"

Genius Bar Reservation and Apple Support Options - Apple

Outside the USA

Contact Apple Support - Apple Support

Get help with your Mac notebook battery

Learn how to optimize the life of the battery in your Mac notebook, fix battery issues, and get service.

If you see Service Recommended on your MacBook Air or MacBook Pro - Apple Support

That computer is a battery-CAPABLE device. It is not optimized as a battery-operated device. (It is NOT an iPhone.)

Your computer performs best when connected to AC power, such as the power adapter. It can use the full output of the Power Adapter AND when doing especially challenging work could also freely "borrow" power from the battery. In some cases, even with the power adapter connected, the charged state may decline during very stressful work.

When used only on battery, your computer has no extra cushion of power, and may perform more slowly. However, for ordinary non-stressful tasks this may not be objectionable (possibly not even noticeable.)

In general, you should ALWAYS connect a power source when it is possible to do so, and only run on batteries (which could be somewhat slower) when no power sources are at hand. Modern Macs maintain optimum battery charge levels under program control, and will NEVER over-charge. 

When you set it down to use in one place, or set it down for the night, plug it in. Then you won't CARE whether it would drain the battery.

The LEDs in the MagSafe end are controlled by commands from the computer. If the computer has discharged its battery so deeply that it has forgotten the date&time, it could be permantly damaged.

cjod wrote:

Since new, my laptop has been shutting down before it reaches 0%. I first noticed this issue when I went on vacation and left my laptop at home. When I returned home, I pressed the power button and nothing happened. I had to plug it in to get it to power up.

Make sure to completely power off the laptop. Before powering down the laptop, make sure to disconnect all external devices since disconnecting them afterwards may cause the laptop to power back on. Also, avoid touching any keys and even the Trackpad as they can power on the laptop as well.

Here is an Apple article with instructions for properly storing a Lithium Battery (the relevant section is near the bottom of that page):

Batteries - Maximizing Performance - Apple

When I charge it full it takes a very long time to go from 99% to 100% and then when it is at 100% it can stay there for a long time while on battery power. Something is clearly very wrong.

Completely normal. The battery is only being charged about 0.1 - 0.5A at that point.

Plus macOS doesn't actually report the correct battery charge to the user. When macOS shows the battery at 100% charge, the actual charge may be anywhere between 95%-100% (perhaps even a bit lower). The difference between what macOS is reporting & the actual battery charge is not consistent....the delta varies at various charge levels.

I have always used the original MagSafe and 61W power adapter. Coconut battery reports 249 cycles, 5,833mAh full capacity from designed 6,075 and battery health of 96%.

What can I do?

Base 2022 14" MBP M2 Pro, purchased new from apple in June 2023.

If something is running amok, then maybe it is causing the battery to drain more quickly. Plus, the longer the battery was at 0% charge during your vacation, the more likely the battery was damaged where you will notice issues when the laptop is using lots of Energy or whenever the battery charge level drops below 10%.

Unless you have a software issue contributing to the problem, there really isn't anything you can do. Unless the battery condition is "Service Recommended" or fails the Apple Diagnostics, then Apple won't do anything unless you can show them that the laptop powers completely off when the battery charge level has a significant charge. Unfortunately the macOS battery condition & Apple Diagnostics (even the service level diagnostics) no longer do a good job of identifying issues (I had to develop my own test script & procedure to identify problematic batteries).