MEATER: The Only Wire-Free Smart Meat Thermometer on IGG

[Kalidor]

https://www.indiegogo.com/projects/meater-the-only-wire-free-smart-meat-thermometer

Is it possible that a battery and a WiFi & BT module can withstand cooking temperatures?

[SeanB]

Not for long, if you go for well done it will go above 140C and the battery and BT module will both fail, the battery probably explosively, which would be somewhat unhealthy in a gas oven with a naked flame and some volatile organic solvent vapour in a near ideal stoichiometric mix.

[crispy_tofu]

Not to mention the cycling of temperatures... wouldn't last for long
And then there's the people that are going to say that the Bluetooth radiation would poison the food...

[pbendel]

Somebody should do a teardown on the probe, maybe TEG powered from the temperature difference from one end of probe to the other end.  Maybe destructive testing, run a thermal oven hotter that a barbeque (or just use a barbeque) and see if anything fails...

[Marco]

The holder seems to be a charger, maybe they use capacitors to store energy? How much energy does it take to blip temperature say every 5 seconds? It's a pretty chunky piece of metal, you could put quite a lot of capacitance in there and the electronics can be in the tip at relatively low temperatures.

I could see this working, but building it to 59$? That's quite an achievement.

[crispy_tofu]

The holder seems to be a charger, maybe they use capacitors to store energy?

According to the Kickstarter, looks like it uses a AAA battery, which can 'recharge the MEATER up to 100 times'. (unless you're talking about the probe)
There's a battery compartment on the back. 

[Marco]

"Notch: Safe insertion line"

Does that mean that if it's not inserted in a piece of meat that deep it's not safe?

[crispy_tofu]

"Notch: Safe insertion line"

Does that mean that if it's not inserted in a piece of meat that deep it's not safe?

Yep, it'll turn into a projectile. 

[mzzj]

Not for long, if you go for well done it will go above 140C and the battery and BT module will both fail, the battery probably explosively, which would be somewhat unhealthy in a gas oven with a naked flame and some volatile organic solvent vapour in a near ideal stoichiometric mix.

You need only the antenna outside of the meat thus reducing the temperatures to below 100C.

[mikerj]

Wonder how well it works in a microwave 

[Kalidor]

Wonder how well it works in a microwave 

As soon as the door is closed WLan & BT is blocked, no need to switch it on  . You can try it with your phone.
The backers with a microwave oven (combined) will probably complain.   

[kfitch42]

"Notch: Safe insertion line"

Does that mean that if it's not inserted in a piece of meat that deep it's not safe?

Probably.

 I assume the battery is near the tip. This lets them use the meat as insulation to keep from causing thermal runaway in the battery. If they can get a battery rated for "industrial" temp range (125C) they might be OK. Cooking temperatures for meats ( http://www.foodsafety.gov/keep/charts/mintemp.html ) are below 100C. They probably only have a temp sensor (something like a K type thermocouple?) and the bluetooth antenna in the dark part that is not in the meat.

[tom66]

Does it need a battery?  If the bluetooth part transmits only every minute or 30 seconds you could probably get acceptable performance from a bank of capacitors.

A BLE module I have uses 15mA during transmit for around 1ms and sleeps the rest of the time. That's about 15uC for one transmission. Say you need to do 100 transmissions in every cooking session, excluding quiescent losses for now, that would mean you would need 1.5mC, or at 3V about 500uF. That's within the realm of a high temperature electrolytic, or even a few large format ceramic capacitors.

[Bud]

"Notch: Safe insertion line"

They've done their safety research to mitigate liability claims in case people used it as a rectal thermometer

[Marco]

That's within the realm of a high temperature electrolytic, or even a few large format ceramic capacitors.

I'd try 50V X7R ceramic capacitors derated to 12V, LoRa with an external BT/WiFi relay and put it together with 80Au/20Sn solder. That should make it pretty much indestructible.

[fcb]

"DEREK - Your meat is ready!"

What's not to love.

[crispy_tofu]

Obligatory (sfw):

[LukeW]

The holder seems to be a charger, maybe they use capacitors to store energy?

According to the Kickstarter, looks like it uses a AAA battery, which can 'recharge the MEATER up to 100 times'. (unless you're talking about the probe)
There's a battery compartment on the back. 

Energiser E92 AAA datasheet gives the nominal charge capacity as 1100 mAh (at 25C, 25mA discharge to 0.8V)

So charge capacity of each probe should be 11 mAh, assuming 100% efficiency.

[kfitch42]

So charge capacity of each probe should be 11 mAh, assuming 100% efficiency.

The meater page says:

Rechargeable Battery: Lasts 48 hours or more of continuous cooking between charges

I will take a swag at 1 transmission per minute. 48*60 = 2880 transmissions

A BLE module I have uses 15mA during transmit for around 1ms and sleeps the rest of the time.

2880  * 15mA*1ms  = 43200(mA)(ms) = 43.2(mA)(s) = 0.012 mAh

Did I foul up my math? That actually suggests that transmit power is not the limiter. Maybe they are doing 1 transmission per second. Or perhaps they need to transmit BLE at crazy high power (since they are likely to be in something resembling a faraday cage (oven or grill).

[EEVblog]

FYI, the user "meater" was a fake account with a bogus website. Banned.

[Srbel]

It should survive if this is true:

https://ksr-ugc.imgix.net/assets/004/408/809/ebb99ce2817df79798740cec633ae3be_original.gif?v=1440979088&w=680&fit=max&q=92&s=d0a16615401d8f75b76d1113f1d7f5c3

Only goes up to 75,5 oC?

[amyk]

There are ultra-high-temperature batteries available up to 200C:
http://www.steatite-batteries.co.uk/electrochem-lithium-batteries.html

Probably not cheap though, if you have to ask for the price...

[Kalidor]

There are ultra-high-temperature batteries available up to 200C:
http://www.steatite-batteries.co.uk/electrochem-lithium-batteries.html

Probably not cheap though, if you have to ask for the price...

These are non rechargeable batteries, smallest size is AA.
The contents of the batteries are highly toxic and require special disposal procedures, additionally they may explode if shorted.