Sony WF-1000XM4 explodes while charging

File this into the unconfirmed folder for the time being since I am waiting for the original user to post more photos in their post.

In a post on Reddit, user yangcong1982 has reported that while charging their WF-100XM4 earbuds in the case, the right earbud exploded. The user originally purchased the earbuds back in December 2021 and the battery drain issue started about a week ago in the right earbud.OP posted a photo in the thread, which I am posting below.

 

The right looks like it has split open, but the battery does not appear damaged. Of course additional photos would help to see the state of the battery, plus the insides of the earbuds and case. Hopefully we can get more details from the user soon.

Update, the user provided a photo of the battery and it looks like it is damaged. See the battery on the right side, it is split open. The user is on 1.4.2, and the earbuds were purchased in Canada.

In another post on Reddit, user Z1ayer reported that one of the batteries in their earbuds swelled up. The user in one of their replies mentioned that they only noticed this problem since the case was open. They also said they saw no smoke, and felt no heat coming from it the affected battery.

I do not have any details about the firmware of the earbuds for second case or whether the user made use of a fast charger for recharging. It is unknown what could be causing these issues for these 2 users, but swelling and exploding batteries is not a good look for Sony, especially since a new model should be coming this year.

The question now is, are the ZeniPower batteries faulty and need replacing?

Is only a certain batch affected, like from the initial production run?

Could the firmware be at fault?

Or is it a combination of firmware and battery issues?

Unfortunately we do not know, as Sony is keeping a tight lid on all of this and replacing batteries for users in certain regions without charge, even if they are past their warranty period. Supposedly users in the UK are running into issues with getting their units fixed/replaced.

An anonymous comment on the blog did mention that a retail unit which was purchased in the UK shipped with 1.6.1, so it appears Sony is loading this firmware onto the earbuds at the factory already.

There is a massive battery drain/issue thread on Reddit for anyone interested in adding their battery drain issue experience and any replacement information as well for their region.