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Combustion Inc Wireless thermometer probe by Chris Young


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Adey73:

 

Each probe logs all of its data internally once per second, and it will be possible to use the app to save or offload those temperature logs. I have a bunch of ideas for cool things we can let people do involving log files, but they probably won't make the cut for our first release.

 

The timer will probably support 8 probes. Maybe a couple more, maybe a couple less, technically we could support thousands, but the trade-off is memory and battery life for the timer. This is something we're actively optimizing right now, and 8 looks like the right balance of trade-offs.

 

Speaking of battery life, the probe is quite a challenge. We use a somewhat exotic rechargeable chemistry that has the very nice properties of handling very high temperatures and not doing anything unpleasant if it does get too hot. The downside is the energy density it really low—like terrible. To get the probe a lot thinner, we had to go with an absurdly *tiny* battery. This gives us a few mAh of power in the probe, so to get 24+ hours out of the battery we just have to be somewhat clever with how we power up the sensors, process the measurements, write it to memory, and transmit it over Bluetooth. The probe has no WiFi simply because the power requirements are much too high.

 

One happy accident was that while designing our antenna, our RF engineer had the very clever idea to use the food as part of the antenna to get more transmission efficiency at lower power.

 

As for the concern about nasty things leaking out of the probe... Everything we used is ROHS compliant (so nothing really nasty in our electronics) and a leak would be exceedingly unlikely. Once we bond the ceramic handle to the stainless steel tube, it's not coming apart again.

 

 

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ah cheers @ChefChrisYoungi figured that the battery wasn't an issue for that reason; can you speak to charging the probe? i see it comes with a fancy container - will that have a connection for it?

 

6 hours ago, adey73 said:

welcome aboard @ChefChrisYoung

 

You've said elsewhere that each timer could take at least 8 probes, presumably we can name or colour code each probe, but will the app, when's it's finished be a data logger and be able display each probe's temp concurrently rather than skip through them like some of the bbq controllers do? (e.g. whilst using the app on a larger iPad/tablet screen).    

 

And can you speak to how the probe is powered, somebody asked about battery, if it's not commercially sensitive how do you power a small wifi probe for 24hrs: any nasties in the battery that could seep out?

 

the probe is ble (bluetooth low energy) not wifi; the modern bluetooth protocols are good at precisely this kind of thing and absolutely sip power in comparison to a protocol like wifi. you don't really need to poll the probe to ask what the temperature is 50 times a second, say, and as a result you can do stuff that really minimizes the power consumption. it'll be a tiny, tiny battery in the probe.

 

the wifi is in the base station that pairs with the probe and remains outside of the oven; that can pair with your phone / access it over the network / internet and you won't need to worry about having a big phatty battery.

Edited by jimb0 (log)
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7 hours ago, ChefChrisYoung said:

Speaking of battery life, the probe is quite a challenge. We use a somewhat exotic rechargeable chemistry that has the very nice properties of handling very high temperatures and not doing anything unpleasant if it does get too hot. The downside is the energy density it really low—like terrible. To get the probe a lot thinner, we had to go with an absurdly *tiny* battery. This gives us a few mAh of power in the probe, so to get 24+ hours out of the battery we just have to be somewhat clever with how we power up the sensors, process the measurements, write it to memory, and transmit it over Bluetooth. The probe has no WiFi simply because the power requirements are much too high.

 

What about battery life? Most chemistry batteries have limited charge cycles, and most batteries cannot be "deep cycled" before being permanently damaged.

 

Actually some probe sensors (bi-metal) do generate a very tiny bit of electric power from heat. Probably too little to recharge the battery.

 

Wonder if supercapacitor technology can be considered:

 

"----A supercapacitor (SC), also called an ultracapacitor, is a high-capacity capacitor with a capacitance value much higher than other capacitors, but with lower voltage limits, that bridges the gap between electrolytic capacitors and rechargeable batteries. It typically stores 10 to 100 times more energy per unit volume or mass than electrolytic capacitors, can accept and deliver charge much faster than batteries, and tolerates many more charge and discharge cycles than rechargeable batteries.[2]----"

 

dcarch

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Darch:

 

Yes, bimetallics, thermocouples, and other temperature sensing technology generate a small amount of voltage differential from the thermoelectric effect, and if you combine a large number of these junctions you build a Peltier device that could, in theory, harvest some heat to charge the battery—or even eliminate the battery altogether. But in practice it's a finicky and relatively expensive technology that isn't particular good at being miniaturized. It's what I would call a research project.

 

Super capacitors and ultra capacitors are quite interesting, and are something we looked at closely. They weren't a good fit: the temperature limits are not adequate, to get to 3.3V you need to chain several together, which makes them too bulky, and they are quite expensive. This is likely to change over the next 5 years, but this is still a niche technology.

 

In terms of charging quickly, you only get the benefit if you can supply enough current at a high enough voltage from the charging source. Since our charger uses common AAA alkaline batteries, we would have to kill the alkaline battery life to charge a capacitor at a very high rate. As it stands, our battery takes about 10 minutes to get an 80% charge and ~20 minutes for a full charge. In testing, we're seeing around 30 hours of battery life from the probe. 

 

Your concerns about deep discharging are very real for many battery chemistries like lithium polymer, but not a concern for the chemistry that we're working with. And the long-term capacity loss from charging/discharging cycles is minimal. 

 

TL;DR there are a lot of ways you could power a probe, we've looked at this closely and selected an approach that balances cost, maturity of technology, safety, and overall consumer experience.  

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All I can say is that you guys have done an amazing job is getting this gadget to market, overcoming many technical limitations.

 

Things like using the chicken or roast beef as part of the transmitting antenna, when all I can think of is antennas need to be proportional to wave length. or fractional to wave length. 

 

Be careful,  don't sell your device to me. If I get one, the first thing I do is to cut it open to find out how you guys did it. LOL!!!

 

dcarch

Edited by dcarch (log)
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On 2/28/2021 at 5:08 AM, palo said:

I want one too, but a couple of caveats: when is "launch" and price?

p

Coming back to my original question.

 

p

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Launch will be when I'm confident that manufacturing won't become a disaster. Price will be when I'm confident that all of the costs are nailed down. I would like both of these things to be as soon as possible.

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15 hours ago, palo said:

Coming back to my original question.

 

p

 

You will not get an answer until the pandemic is totally over for the whole world.

At this point, even GM had to shut down their factory for lack of chips.

 

dcarch

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8 hours ago, mgaretz said:

I'm going to be one of the beta testers!

 

 

grats on getting a bunch of signups, haha. 

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1 hour ago, dcarch said:

 

You will not get an answer until the pandemic is totally over for the whole world.

At this point, even GM had to shut down their factory for lack of chips.

 

dcarch

Not to be picky but which factory and for how long? The pandemic has certainly affected supply chains but consumer goods are still available.

 

p

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14 minutes ago, palo said:

Not to be picky but which factory and for how long? The pandemic has certainly affected supply chains but consumer goods are still available.

 

p

 

https://www.cnbc.com/2021/03/03/gm-extends-plant-shutdowns-due-to-global-semiconductor-chip-shortage.html

 

https://www.theverge.com/2020/3/18/21185015/honda-coronavirus-factory-shut-down-fiat-chrysler-ford-gm

 

Disruptions to manufacturing due to the pandemic is worldwide for all industries, not limited to the automobile sector.

 

dcarch

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Supply chains are a mess. Shipping is a mess. And new products are always the lowest priority for everyone. It only takes one component being delayed to up-end everything.

 

Moreover, everything is a lot harder and slower because travel is restricted or impossible. Normally we'd have our engineers on the factory floor working through issues with our manufacturing partners; that isn't possible right now, so you have to FedEx things around and use Zoom calls to figure things out. Things that could be solved in a day can easily take a week because you can't all be together on the spot.

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is it possible yet to  see a video of the temperature on the timer as the probe gets stuck into something?

(yes, that's as exciting as my life gets, even without Covid)   

 

 

 

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“Do you not find that bacon, sausage, egg, chips, black pudding, beans, mushrooms, tomatoes, fried bread and a cup of tea; is a meal in itself really?” Hovis Presley.

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On 3/6/2021 at 6:23 AM, ChefChrisYoung said:

Supply chains are a mess. Shipping is a mess

Yes. Best wishes to you for trying to develop what looks like an interesting product in difficult times. It will come down to what you produce and how well v1 is received. Don't rush it.

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  • 3 weeks later...

 

 

the Singularity sent me this...

 

Excellent conversation covers not just Combustion inc, but the beginning of Modernist Cuisine.

“Do you not find that bacon, sausage, egg, chips, black pudding, beans, mushrooms, tomatoes, fried bread and a cup of tea; is a meal in itself really?” Hovis Presley.

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