Current monitor for mini-solar panels (18V, ~20W)

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BeanieBots
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Re: Current monitor for mini-solar panels (18V, ~20W)

Post by BeanieBots »

Thanks for running that by your "friend".
My take from 'his' response ... "In practice, achieving a net positive energy output from such a system is challenging." ... is that although not easy, it is indeed possible.
I appreciate that it sounds a little bit like using an electric motor to drive a generator, but there is external input in the form of heat.
The bit where my knowledge is lacking is whether or not it is possible to have a heat pump with the required temperature differential to run the engine and still run at the required efficiency. (ie, is that possible even if we ignore inefficencies such as heat loss and friction).
The carnot cycle can at best get to 40% due to laws of physics. Don't know about heat pumps and don't seem to be able to find out despite many hours on Google and even a chat with your 'friend'. I've seen claims up to 600% but 400% is quite commonly banded around. You only need 34% on the engine and 300% on the pump to get a net output.
So, now that I've invented the "energy for free" engine. Next step.....build one. :lol:
Banter aside, I'm pretty sure it's possible.
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Re: Current monitor for mini-solar panels (18V, ~20W)

Post by PeterN »

Hi BeanieBots
I did sleep well, but not without dreaming of Stirling motors :-)

… and then found these people sitting just around my corner:
https://www.oekofen.com/en-gb/search/se ... -stirling/
https://www.oekofen.com/en-gb/myenergy365/

Not exactly your approach … but perhaps worth reading
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Re: Current monitor for mini-solar panels (18V, ~20W)

Post by BeanieBots »

Again, thanks for an interesting read (though their auto translation leaves a lot to be desired).
Nice to see that at least someone is investing in the sadly forgotten Stirling technology.
As I've already mentioned, they only need heat to run and there are many sources of that! (many just being waste :( )
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Re: Current monitor for mini-solar panels (18V, ~20W)

Post by PeterN »

I was really surprised how they integrated the electrical generator into the motor!
There seems to be a massive copper loop + moving permanent magnet to produce 600W!

https://www.microgen-engine.com/technology/
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Re: Current monitor for mini-solar panels (18V, ~20W)

Post by BeanieBots »

I've never tried a Free Piston version myself but they are much simpler mechanically with essentially only one moving part.
Never really saw the point because my simple mind was always stuck on the requiremnt of rotary motion being required for anything useful and just thought of them as a novelty.
When you see it in a picture it becomes obvious and so beautifully simple!
My understanding of Free Piston Stirling enginess is that it can be quite a task to get them to 'resonate' and work well but I'll stick with good old pistons myself for now.
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Re: Current monitor for mini-solar panels (18V, ~20W)

Post by PeterN »

Yes, this is a very focussed piece of engineering as it boils it down to just a few linear moving parts.
I was wondering why they didn't even replace the planar spring with a repulsive permanent magnet.
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Re: Current monitor for mini-solar panels (18V, ~20W)

Post by BeanieBots »

[Local Link Removed for Guests] wrote: [Local Link Removed for Guests]Fri Sep 06, 2024 9:53 am Yes, this is a very focussed piece of engineering as it boils it down to just a few linear moving parts.
I was wondering why they didn't even replace the planar spring with a repulsive permanent magnet.
Good question. I have lot of knowledge about magnetism with coils/tx'fers and associated core materials but know very little about permanent magnets and when they move.
Besides eddy currents created in nearby metallic objects and their associated current/resistance losses, is magnetic fource truly "friction less".
Maybe eddy currents is the reason they don't do it??
Is magnetic attraction/repulsion a 'perfect spring' with no losses? (excluding eddy current losses which may even exist withing the magnet itself during motion)
Just an asside, all the linkages in my latest engine design use magnetic couplings. The pivitol ones are virtually friction-less. Even better than a full ball-race bearing. The straight links (with only tollerance error movement) are held in place with magnets which makes it unbelievably quick to replace. (maybe that should read as "fiddle with" rather than replace?). The much lower torques and lack of explosions make that possible. Don't think doing that between piston and crankshaft in a petrol engine would work too well.
I think I need to properly document all of this and post it on the 'Stirling Builders Site' rather than clutter up this site with so much OT stuff.
I can then try and draw them here to learn how to measure their engine's power and speed with an ESP.
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Re: Current monitor for mini-solar panels (18V, ~20W)

Post by PeterN »

Hi BeanieBots
Off topic … but still interesting :-)
http://viessmann.com.ua/images/uploads/ ... _units.pdf
Please look at page 5 for practical operation efficiency values
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Re: Current monitor for mini-solar panels (18V, ~20W)

Post by BeanieBots »

Nice to see that the technology is at last taking off.
Mr Stirling should be very proud.
I've been pushing it for many years now but could not get anyone interested.
Reminds me of a similar time back in the early 80's. A radio-ham friend and I had the idea of using a 433Mhz hand set fitted with DTMF to get a repeater station to call another repeater and eventually send to another handset. Such a system could use a numerical key pad to call another specific handset that was too far away for direct radio link. Does that system sound familiar?
We took it to Maggi Thatcher (as you probably know, coded signals from HAMs is/was not legal on 433Mhz) and we got a categoric NO CHANCE.
Just about everyone on the planet now has a similar device to what we were refused permission to do.
And they don't even need a licence to use it!
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