Best peltier junction to light an LED from a hot coffee mug?

[Triode]

I've never used a peltier junction, so I don't really know what the power/efficiency considerations are for them. Would one reasonably be able to light one or a few red LEDs by being mounted between the bottom of a mug full of hot coffee and a small heat sink? What kind would work best for this?

 

[ronv]

I tried this once on the stove just to see. I thought the voltage was low but couldn't remember the numbers. But..... Here is one made for power generation. It has to be pretty hot and pretty cold, then the current is impressive, but the voltage is low.

**broken link removed**

 

[Triode]

I looked up suggested serving temperatures for coffee and got 71 to 85c, room temperature is usually 22 to 25c. So that means my dT would be, at best, 46 to 64 c, which on that plot gives me 1.3V@0.65@ to 1.5V@0.9A. That should be enough to light atleast one red LED, though they usually like about 2V, most that I see say 1.8-2.2, and I have to take into account that the heat sink will probably warm up quickly. So I'm not really sure if it would work. I guess I could use 2 of them, but were already looking at $20 or so here.

 

[ronv]

Maybe you could wire up a Joule thief.

 

[Dr_Doggy]

plus you could get another 20 degrees if you used iced salt water ,

im not sure how these things work exactly, but i notice some of these have less voltage and smaller temperature differentials, in this other datasheet, if im reading correctly you will get 12watts out of a 30degree difference

https://www.lairdtech.com/WorkArea/linkit.aspx?LinkIdentifier=id&ItemID=4560

...there may be even better ones out there

 

[jpanhalt]

Glad you started this thread. About 3 years ago, I looked into TEG power for a stand-by circulating pump for household heat and didn't find anything. I have dual fuel (propane and and outside woodburner).

Found another site that actually includes that application: **broken link removed**

Wrote for pricing. At this point, your project looks quite feasible.

John