Sauna users overheating? Testing a fix for Apple Watch sauna shutdowns.

[CoachBobK]

"I’m tired of my Apple Watch Ultra 2 hitting 'Thermal Shutdown' 12 minutes into a 190°F session. I lose my recovery data and I'm pretty sure I'm cooking the battery.

I’ve spent the last month prototyping a snap-on shield using Encapsulated Silica Aerogel (thermal conductivity ≈0.015W/m·K) and a silicone "Bio-Sink" gasket.

The Goal: Keep the watch under 110°F for a full 40-minute session.

It’s a 'Dead-Front' design—no screen distractions, just Siri for timers and continuous heart-rate tracking. I’m making a small batch of 10 'Founder’s Beta' units for field testing this month.

If you're an 'Optimizer' who hates losing data, would you actually use something like this, or is it just me? DM if you want the data logs."

 

[Basic75]

I don't get it. Why do you even (want to) wear any watch to the sauna?

 

[ScanTheNavian]

Out of respect for Finns, temperatures in saunas should always be measured in Celsius and never Fahrenheit. Same with how the measures of a sauna are always written in number of beer bottles and not meters.

 

[Ifti]

I don't get it. Why do you even (want to) wear any watch to the sauna?

Precisely!!

 

[MacCheetah3]

I’m not sure how you intend to defy physics.

Environmental Requirements​

• On-wrist operating temperature: –4° to 130° F (–20° to 55° C)
• Operating temperature: 32° to 95° F (0° to 35° C)
• Nonoperating storage temperature: –4° to 113° F (–20° to 45° C)
• Dive operating temperature: 32° to 104° F (0° to 40° C)
• Relative humidity: 5% to 90% noncondensing
• Operating altitude: –1600 feet to 29,500 feet (–500m to 9000m)

Apple Watch Ultra 2 - Tech Specs - Apple Support

Apple Watch Ultra 2 - Tech Specs

support.apple.com

[...] my Apple Watch Ultra 2 hitting 'Thermal Shutdown' 12 minutes into a 190°F session.

An actual ‘fix’… Place/leave your hand in cool/cold water(?)
Or, as already stated by others, don’t wear an Apple Watch or related product.

I'm pretty sure I'm cooking the battery.

From Oura:

[...] extended exposure to extreme temperatures (below -20°C / -4°F or above 60°C / 140°F) may lead to battery damage.

Product Safety & Use

This article outlines best practices, key information, and safety information to keep in mind while using your Oura product.General UseMemory CapacityBattery & ChargingCare & MaintenanceRin...

support.ouraring.com

 

[maflynn]

"I’m tired of my Apple Watch Ultra 2 hitting 'Thermal Shutdown' 12 minutes into a 190°F session. I lose my recovery data and I'm pretty sure I'm cooking the battery.

Yeah, I think I can go out on a limb and say that you're largely damaging your watch for no good reason

The Goal: Keep the watch under 110°F for a full 40-minute session.

The solution is quite easy - stop wearing the watch in an environment it was never designed to be in

 

[babalougots]

Hmmm... I wear my Series 7 Ti all the time in the sauna. Sauna temp 180-190 degrees. In sauna for about 15 minutes. No issues. Once in a while I bring in my iPhone 15 Pro to sauna and have had the phone shut down due to heat.

 

[ScanTheNavian]

I don't get it. Why do you even (want to) wear any watch to the sauna?

Swedes like to time how long they can be in a sauna with a Finn. High score and stuff.

 

[erihp]

next youre gonna wanna charge it in there too.

 

[erihp]

Hmmm... I wear my Series 7 Ti all the time in the sauna. Sauna temp 180-190 degrees. In sauna for about 15 minutes. No issues. Once in a while I bring in my iPhone 15 Pro to sauna and have had the phone shut down due to heat.

Gotta learn to disconnect man. Youd get a hearty scoff from me seeing you on the phone in a sauna. youll also probably creep others out.

 

[CoachBobK]

I’m not sure how you intend to defy physics.

Apple Watch Ultra 2 - Tech Specs - Apple Support

Apple Watch Ultra 2 - Tech Specs

support.apple.com

An actual ‘fix’… Place/leave your hand in cool/cold water(?)
Or, as already stated by others, don’t wear an Apple Watch or related product.


From Oura:

Product Safety & Use

This article outlines best practices, key information, and safety information to keep in mind while using your Oura product.General UseMemory CapacityBattery & ChargingCare & MaintenanceRin...

support.ouraring.com

Spot on with the specs—Apple is clear that 113°F is the limit for battery safety. That’s exactly why I’m using Silica Aerogel (0.015W/m·K). It’s the only material with a low enough thermal conductivity to maintain that 90°F+ Delta in a 2mm profile. I’m testing the 'Internal Thermal Log' this week to prove it keeps the watch under the 113°F 'Nonoperating' threshold. Would you be interested in seeing the internal temp data once the log is done?

 

[MacCheetah3]

Spot on with the specs—Apple is clear that 113°F is the limit for battery safety. That’s exactly why I’m using Silica Aerogel (0.015W/m·K). It’s the only material with a low enough thermal conductivity to maintain that 90°F+ Delta in a 2mm profile. I’m testing the 'Internal Thermal Log' this week to prove it keeps the watch under the 113°F 'Nonoperating' threshold. Would you be interested in seeing the internal temp data once the log is done?

I would be interested in the results. I’m not familiar with that substance. However, based on your description and a little research… Feel free to correct/enlighten me… Your intent/plan is to seal out the (extra) heat?

 

[babalougots]

Gotta learn to disconnect man. Youd get a hearty scoff from me seeing you on the phone in a sauna. youll also probably creep others out.

Where I go, I'm not the only one... I do agree, though. It's a little sus...

 

[xDKP]

I wear mine all the time for the tracking - and a simple sweat band around the wrist to cover the watch does the job

 

[sifpilsen]

Have you considered to be kind and unwind, in the sauna? No gadgets, you are there to relax and cool down in the water every 15 minutes. Enjoy an hour or two of disconnect and no health data recorded. We are talking 1-2 hours, 4-8% of the days 24 hours you're loosing data for. Otherwise, the sweatband suggestion seems like the way to go.