Product
Fitbit FB512BKBK
Category
Wearable
Report number
20260713-E4A37-2147313996
Ownership age
About 55 months to failure (from purchase date when reported)
Failure type
Overheating
Incident narrative
SaferProducts.gov consumer incident report 20260713-E4A37-2147313996. Severity: Incident, No Injury. Product: Fitbit FB512BKBK (Fitbit Sense (first generation) advanced health smartwatch, released September 2020. A wrist-worn fitness and health tracking smartwatch with a square AMOLED touchscreen, aluminum housing, and a silicone wristband, worn continuously on the wrist including during sleep. Color: Graphite. The underside of the watch has a stainless steel sensor plate that sits in direct contact with the skin, housing the heart rate, SpO2, and skin temperature sensors. The device contains a rechargeable lithium-polymer battery and charges via a proprietary magnetic charging cable. The battery in this device swelled, deformed the sealed back plate, and leaked fluid.). Incident: I own a Fitbit Sense (first generation), purchased on November 28th, 2021, and worn daily on my wrist as a fitness and health tracker. I was the only user. In January 2025, Google notified me that my device was among those identified as at risk of the battery overheating. I confirmed my device was impacted, installed the firmware update, and received the $50 appeasement Google offered to affected owners. On July 8th, 2026, the heart rate sensor light on the underside of the watch stayed illuminated and would not turn off. I rebooted the device, after which the heart rate sensor stopped functioning entirely and never worked again. The watch had not been dropped, struck, or exposed to water beyond normal use. On July 13th, 2026, I noticed the metal sensor plate on the back of the watch the surface that sits directly against the skin was raised and no longer flush with the housing. When I pressed it gently it moved back down, then rose again on its own. When I pressed it, a small amount of liquid came out of one corner of the plate. The back of this watch is a sealed, adhesive-bonded assembly and is not designed to move. Based on these symptoms, the lithium-ion battery appears to have swelled
Official report number: 20260713-E4A37-2147313996. Search that ID on SaferProducts.gov or match it in the CPSC public database export to verify this record.