702428 Battery,Compatible with Sony Battery for WF-1000XM4 Charging Case P/N: LP702428 3.85v 520mAh

My earbuds were draining their battery like there was no tomorrow and figured with the help of iFixit I could handle a battery swap. I'm handy but ever rarely tinker with smaller technology, but this was a breeze and the battery fits perfectly and works as expected!!!

Own a pair of the XM4s that had battery issues. I know that there is a huge issue on these and a debate on what is causing charging issues. Some think it is firmware related. After my experience, I am convinced that it is the batteries and if the firmware plays a role, it is in how it changes the charging speed or some other variable. Of course this is a guess. For ref...My firmware was at 2.0.0, when my battery issues started. I was unable to get the buds to charge past 70%. Even at that, I was dealing with a flashing red case. I decided that the case battery had failed and swapped it out. Sure enough, the old case battery was swollen. It was clearly bad. I was surprised to see that the new case battery did not resolve the flashing red case issue. I could now get the buds to charge fully though. Even though I could now get the buds to fully charge, the right bud would die in 10 minutes. The left bud would die in about 15 or so minutes. I decided to also swap the batteries in the buds. And for those wondering.....it was not that bad of a job. The only real issue was...I could not get the cable to release after I lifted the black plastic latch...but it turns out that you can get the battery out without getting that cable loose. Now here is where the second Aha moment occurred during this repair. (The first was the flashing red light after the case battery was swapped) As I had never done a battery swap in an earbud before, I wanted to make sure that I had done things correctly before gluing the bud together. While testing it, I noticed that I was also getting totally different battery readings from my left earbud. Now keep in mind, I had not yet touched my left earbud. I had only swapped the battery in the case and the right earbud. This was interesting enough that I ran several test. And the left bud seems to have a significantly longer life than before. It was nothing like the right and the new battery....but much better than it had been. I then swapped the battery in the left earbud out too. I should note that I found the old batteries in both the left and right earbuds were slightly swollen. I have since upgraded to the 2.0.1 firmware on the new batteries. I now have weeks of using the buds and they operate like when they were new. There are no more charging issues at all. My takeaways... The interconnection between the case and between the buds is playing some role in the battery drain issue and confusing things. (Best guess....the right bud advises the battery level of both buds..and this is why it seems to drain 5%faster) You cant go by what the drain readings are telling you. It is entirely possible that the intercommunication is point you in the wrong direction. I now fully believe the issue is a battery issue....and the only way to truly clear the issue is to replace all 3. Yeah, the firmware may highlight the failing batteries...but if all 3 batteries are swollen, that is not software.

I was having trouble finding replacement batteries for my WH-XB910N Sony Headphones. I let mine stay dead too long and it wouldn't charge, and then I got a replacement that was 550mAh instead of 520, but that wouldn't charge either (flashed orange for the "abnormal temp" warning). But then I popped this in and not only did the headphones turn on, but they charged! I'm so glad to have these back since they are still in like-new condition otherwise (body and pads are still in great shape).

Unlike several other options, this worked and charged. Only negative is it's is slightly thicker than the original battery, so the inside of the case doesn't clip fully into the external case. It's still usable but something to keep in mind.

Fit perfectly in my headphones case.

I was a little worried to put a aftermarket battery in the case of my expensive headphones, but after a while I had no choice but to try something or get new headphones. This worked perfectly. I followed a video online and this took under 30 minutes. The battery life on this case is exactly as it was when I first bought the headphones. They charge up by headphones 3-4 times before I need to charge the case up again. The replacemnet battery looked identical to the OEM one I removed from the case, it may even come from the same factory. Just keep an eye out for the magnets that hold your headphones into the case, they may fall out when opening the case to replace the battery. If you reverse the polarity of the magnets when putting them back in, the headphones will be repelled instead of sucked into the case. I had to learn the hard way when putting the case back together.

Did you know your earbud case has a battery and that you can easily change the battery when needed? It’s true! This battery fit my Sony and after I changed the batteries in the buds realized this need changing as well. It’s very easy - look on YouTube for your particular model, Amazon has whatever battery you need and you will soon have earbuds that charge and will recharge in their case! It took me 5 or 6 minutes to change it out and was easily done,

Swapped out battery with no issues. It charged ONCE, and has not charged since. Getting the blinking red light on case (which I wasn't even getting before...I replaced it because it was getting weak, and wouldn't charge the buds fully anymore). Now, the only way I can charge the buds is by putting them in the case, and plugging the case in.