Stove that charges your cellphone

[JonnyBoats]

Interesting startup: http://biolitestove.com/

I wonder how efficent these are? I suspect they use a peltier device.

Then again in an emergency like Hurricane Sandy efficiency is not the primary concern. These were being setup on the streets of Manhattan to charge cellphones and make tea for people without power.

https://plus.google.com/photos/109794669788083578017/albums/5806415287457734209/5806415295118694514

[ftransform]

now for a kerosene heater version

[rr100]

Useless gimmick, like the small solar chargers it has a LiIon battery inside, otherwise they'll have a 100% return rate.

The BioLite CampStove uses a small internal fan to create airflow, which, in conjunction with our uniquely designed fuel chamber, creates an ultra-efficient fire with highly improved combustion. The heat generated by the fire is converted into electricity in our Power Module which automatically recharges the lithium ion battery powering the fan. Surplus electricity powers a USB outlet allowing you to charge small electronic devices.

Can't find much about the power but it says:

iPhone 4S (2G): 20 minutes of charging provides 60 minutes of talk time. Charging times vary by device and by strength of fire.
...
Charging times vary by device, as well as by the strength of the fire and other variables like outside temperature. For an Apple iPhone 4S (2G), 20 minutes of charging with a strong fire can provide you with 60 minutes of talk time.

As that iPhone has 14h talk time on 2G it means you'll need 14 times more = 4.66 hours of "strong fire" to charge your phone (note the language, it isn't clear if you also use the Li battery from inside the stove during that time!).
You get quite a few charges from one of those "power packs", even a 10-11+Ah will be much smaller/lighter/cheaper than this stove (even if you include some other decent reliable stove).

Plus fan+liion battery+fire going for tens of hours (if you want to get multiple charges, as you get from a big power pack) don't go well together.

[tom66]

I am also worried that the strength of fire affects the charge rate. Does that mean the output isn't a stable 5V?

And I somehow doubt the first concern in the third world is whether or not your iPhone can be charged.  How close are you to a cell tower anyway, if you don't have electricity?

[rr100]

Like the chargers with small solar panel: it has internal battery that does most of the lifting and can probably charge your phone even without any fire. Problem is the world is full of small battery-powered "usb chargers" so they add the stove to make people think they can go on forever on burning wood. Which is not the case, for any practical situation.

[tom66]

They need to pick a more rugged, slightly more expensive solution. A NiCd will last longer (if not abused) but people will get their knickers in a tangle about it containing cadmium.

[SeanB]

You could get 10% more out of it by disconnecting that green LED that is just there as a power indicator.

If you want to DIY one you just need an old cooler box with a petlier block, and keep one side near ambient and the other under 100C. then it will generate a usable current.

[rr100]

@tom: LiIon is perfectly fine as long as you don't have to keep it for five hours at a time centimeters away from a "strong fire" only to give you the energy to charge a ~20 gram battery. That from a largish 1kg contraption.

[FenderBender]

They might be using some type of thermocouple. Bleh looks gimmicky you guys are right.

But perhaps it looks interesting if it's done right.

[tom66]

They mention a TEG here, I guess that means Peltier junction.

http://www.biolitestove.com/homestove/homestove-technology/

[rr100]

Interesting thread about a similar project, with some good links and some numbers:
http://www.candlepowerforums.com/vb/showthread.php?336328-The-PowerPot

Overall looks like an interesting topic, however still looks like it would fit more of a permanent/semipermanent setup (just like solar). And you have to remember you also need "cold" not only "hot" to generate power.

For emergency or "woods" scenarios still not that useful I think. Best comment that puts things into perspective from that thread:

My Jet Boil allows me to boil a liter of water in something like 2.5 minutes.

It is probably exaggerated (but not much, those units boil half a liter water in just above 2 min, average over the life of the canister), and they're small, light, robust and mostly bulletproof (I'm not talking about that particular brand but about any similar good product as opposed to the stove with LiIon batteries and fan included). Both in emergencies and when you travel away from power for extended periods of time you aren't making extravagant gourmet dishes to justify keeping the stove running for 5 hours.

[T4P]

There's a more efficient method using gas : It's called a portable generator that uses steam from the boiling water

[Sionyn]

strong fire

this is a epicfail in terms of a project bet it comes with a high price too

[peter.mitchell]

This product as a concept is nifty, the actual product sucks. A 4w solar panel and some 18650s would be just as good and would have a number of advantages, like leaving it unattended to charge while you go for a hike without worrying about the world catching fire.

The biolite stove claims 2w nominal 4w peak... most top of the line smartphones have 2Ah~ batteries..  that's close to 4 hours to charge provided the phone is turned off, that is quite a while to leave a little fire burning...

Just get a usb battery pack,  in most cases they'd do the same job, unless you really ARE in an emergency, but then you wouldn't really be able to choose what you're bringing anyway.