AirPods Max 2 battery drains to 1% in Smart Case
Airpods Max 2 drain to 1% while in their "Smart Case" (Not Smart).
iPad Pro, iPadOS 26
Question marked as
TL/DR executive summary: Check that your foam ear pad inserts are on the correct side and not upside down. Read on for details.
I was also experiencing significant battery drain of my new AirPods Max 2s while they were stored in their case. I may have discovered one potential cause, though I was not scientific enough in my troubleshooting to be certain. Before discovering that cause, I first ended up removing the headphones from my account and then followed the instructions to restore them to factory settings. Then I followed the process to add them back on my iPhone.
Right away, they were still not acting normal, as they were glitchy in connecting to my Apple TV, and the button on top would not switch them between noise-canceling and transparency modes.
It was at this point that I noticed that one of the ear pads (in my case the one on the right side) was upside-down.
I had only discovered by accident previously that the foam pads in the headphones are removable. This feature is not mentioned prominently in the setup/operating instructions. They attach with magnets. When you remove the inserts, they consist of the foam pad ring that goes around your ear, and also a screen inside the ring that goes across the speaker when inserted into the headphones.
There are two important things to note while looking at the ear pads. First, holding one up to light and looking through that screen in the middle, you will see an "L" or an "R" to indicate which side they go on. You should also notice there is a little hole on one side of the part inside the foam ring. That hole is meant to align with a sensor inside the headphone cup. That sensor is what detects that you're wearing the headphones. As such, it's critical to make sure the L or R are right-side up when you insert them, so that the hole aligns with the sensor. If they're upside down, the sensor will be blocked. This is definitely what was preventing me from switching between noise-canceling and transparency modes.
Here's the important part for the battery drain subject of this thread. I think by blocking that sensor, the upside-down ear pad insert was also causing the headphones to 'believe' that they were still being worn, thus preventing them from going into "sleep mode" while stored in their case. As a result, the battery drained as though the headphones were being worn and used overnight, even though they were inserted in the case.
I'm a little surprised Apple didn't design the ear pad inserts so that they would only go on the correct side and only fit when inserted in the correct orientation. I can't be certain that the device reset isn't what fixed the battery drain issue, but I strongly suspect it's actually the upside-down ear pad coving the sensor that caused the problem. I hope somebody from Apple reads this and investigates that possibility.