Whoop user claims device's battery exploded on its own

Imagine heading out for errands and returning to a burned smell wafting through your home. That’s what happened to one Whoop user who shared their shocking story on Reddit. The fitness tracker’s battery pack, left idle on the bed, apparently overheated and melted, damaging the mattress and sheets. It wasn’t plugged in or charging at the time, according to the post.

The user, posting under the handle value-investor in the r/whoop subreddit, described the scene in detail. They had charged their Whoop device earlier that morning and left the battery pack behind before stepping out. When they got back, the damage was done. The pack had fused to the fabric, leaving a hole in the mattress. Luckily, it didn’t escalate into a full fire or worse.

“It seems like it melted on to the sheets because it’s like really stuck on there and the whole it even made on the mattress,” the user wrote. They also shared a couple of pictures for proof. Check them out below:

They added that the battery was about half-charged and emphasized it wasn’t exposed to direct sunlight or any obvious heat source. The room wasn’t sunny, and the pack was just sitting there on the bed. This detail sparked a lot of questions from other users, with some wondering if a focused beam of light through a window could have played a role, like magnifying glass on an ant. But the original poster shot that down, saying their setup didn’t allow for that.

The post quickly blew up, racking up hundreds of upvotes and comments. People were freaked out. One commenter called it “creepy as hell,” while others shared their own worries about leaving devices unattended. A few mentioned feeling paranoid now, with one user joking about storing their extra packs in the sink just in case. Safety concerns popped up too, like imagining it happening while wearing the device or during sleep.

“Haha seriously. I don’t want to wear this thing anymore. Imagine wearing it in the middle of the night and burning through your skin!!” the original poster replied.

Whoop jumped in fast. Their official account messaged the user privately to investigate. But the follow-up wasn’t what the poster hoped for. Whoop asked a bunch of questions and requested the damaged pack back for analysis. They offered a replacement sensor, but stuck to the 4.0 model — no upgrade to the newer 5.0, and no word yet on covering the ruined bedding.

Community advice poured in, urging the poster not to ship the pack back right away since it could be evidence if things escalated to a claim or lawsuit. Some suggested contacting consumer protection agencies or even tipping off media outlets. A few pointed out lithium-ion batteries, common in wearables like Whoop, can overheat if faulty, though spontaneous issues are rare without charging or damage.

This isn’t the first time Whoop users have reported battery troubles. Over the years, Reddit threads have documented similar scares, like a 2023 case where a battery pack melted with a burning plastic smell, a 2024 incident of a battery smoldering while charging, and an older 2019 report of a Whoop 2.0 charger that “done ‘sploded.” Adding to the company’s quality woes, we also covered a serious concern with the Whoop MG in May, where multiple devices died within hours of use.

We’ve reached out to Whoop for comment on this incident and will post an update if and when we get a response. In the meantime, users might want to keep an eye on their gear and charge in safe spots. No one wants a fitness boost turning into a fire hazard.