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!!!

la medida y voltaje del estuche de mis audifonos

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.

Volvieron a la vida mis Audifonos A pesar de que la falla principal de estos audifonos es la pila su sonido es genial Llevo desde enero con esta pila y no he tenido problemas

Good fix for charging issues!