Thread: Stirling engine science project idea.

Hi everyone. I would like if people could give me some tips on how to approach my science project.
I decided that i want to try to use a Stirling engine as a charger for a smartphone (possibly an overnight one?). I was thinking that to do this I would need to connect the engine to a USB port.
Please give me advice guys, much appreciated

Originally Posted by mrjohn

Hi everyone. I would like if people could give me some tips on how to approach my science project.
I decided that i want to try to use a Stirling engine as a charger for a smartphone (possibly an overnight one?). I was thinking that to do this I would need to connect the engine to a USB port.
Please give me advice guys, much appreciated

It seems like a pretty crazy way to charge your phone, but as a project, you might learn something from doing it.

You will need to use your engine to drive a generator, which could be either a-c or d-c, but ultimately you need to provide whatever d-c voltage your phone charger puts out. Take a look at the phone charger to see the voltage rating stamped on it.

The simplest way is to use an alternator to generate 120 volts ac and just plug your phone charger into the alternator output. If you use a d-c generator of the appropriate voltage, you would hook it up to a USB connector just like the one that plugs into your phone.

Originally Posted by mrjohn

I decided that i want to try to use a Stirling engine as a charger for a smartphone (possibly an overnight one?). I was thinking that to do this I would need to connect the engine to a USB port.
Please give me advice guys, much appreciated

This can work. I'd recommend connecting a DC motor to the Stirling engine. This will function as a generator. Find a motor that will give you about 6-7 volts at normal operating speed, then regulate it down to 5 volts with a 7805 or equivalent regulator. You will need to generate at least about 2 watts to charge the phone.

thanks guys, that's enormously helpful! So does this project seem doable? It's something that struck me as potentially useful and fun to do.

Hey mrjohn, thats a pretty cool project. Are you building the engine from scratch or are hoping to attach a already built one to charger?

Originally Posted by burkey

Hey mrjohn, thats a pretty cool project. Are you building the engine from scratch or are hoping to attach a already built one to charger?

Thanks! I'm hoping to source a cheap one, but if that isn't possible I intend to make one.

I'm sure you're already all over it, but found this StirlingBuilder.com - How to Build a Stirling Engine while browsing around looking at your idea... I think perfectly do-able idea. Might actually be quite nice, light a candle at night, ahhh nice "night-light" but what's this? My phone is charged too?? Awesome I say Awesome!

Originally Posted by burkey

I'm sure you're already all over it, but found this StirlingBuilder.com - How to Build a Stirling Engine while browsing around looking at your idea... I think perfectly do-able idea. Might actually be quite nice, light a candle at night, ahhh nice "night-light" but what's this? My phone is charged too?? Awesome I say Awesome!

Thanks a lot for the link burkley. I really appreciate the help.
Your check is in the mail

You could also add thermoelectric generators to increase the amount of current you produce.

Thanks everyone for the replies, great so far.
Anyone want to wager a guess as to how much all this is going to set me back e.g the motor, regulator, possibly the thermoelectric generator?

Well...the Peltier cells cost about 5 bucks each
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Any electric motor will work as a generator...just not as well as purpose build alternator or generator. You could try salvaging one out of an old cd player or cassette player or some other junk equiptment. Same thing for all the components of regulating circuit. The capacitors and regulator chip can easily be salvaged from old electronic boards.

Now the parts for the stirling engine...I'm not sure. The one in video posted was barely able to spin a cd...so you need something with a lot more ummpf. It's one reason I suggested adding peltier cells to help with the current generation. However, if you can post a design for your project engine...I'm really good at thinking up household stuff that can be used to build it.

The peltier cells are fun as hell to play with. They have a hot side and a cold side. If you apply heat to the hot side or cold to the cold side..or both...the difference in temperature will create a voltage on the wires...the bigger the difference in temperature..the larger the voltage. Alternatively, if you apply a voltage to the wires, the hot side will get hot and the cold side will get cold. My buddy used them to build a single beer insta-cooler that could cool a luke warm beer to drinking temp in a couple of minutes...it was pretty bad ass.

I've also seen them used to make campfire cell chargers. Two cast iron skillets were bolted together, bottom to bottom, with the cells inbetween. You just set the aparatus over the campfire and fill the top skillet with water. The bottom skillet gets hot, and the top one stays relatively cool. Adding ice to the water improves performance.

I'll definitely get a few of those peltier cells if I can, they seem like they'd be pretty essential.
As for the design, I've nothing concrete worked out yet. I figured something along the lines of what it is the video there would d, except with more oomph as you said!
I intend to build a few different ones using different types of.. cans i guess? to see which works the best.

quick update for anyone that sees this: the project proposal was rejected as it was felt I had not developed it enough for submission into the competition i was trying to enter. Oh well, maybe next year