Reeling Motor Project - Help Please

  • #26
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This is the one that's set to be delivered next week, my project is due on the 23rd.
Aideenpeen peltier module 12v. ....

But for an estimate, I would be EXTREMELY HAPPY if I got 48W. 12v and 5.8 A max. It's risky because 48W is near the maximum current and voltage but we have also ordered two different peltier brands to see which one is the most efficient.
See above post. Here's an example - this guy used 16 of the larger peltiers, and managed to get 14 V and 1 amp for 14 watts. So less than 1W per Peltier. You will need smaller motors.

 
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  • #27
anorlunda
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Here is a curiosity. There are a number of miniature winches intended for use in radio controlled models. Their specifications can be useful to you as a benchmark. Here is just one as an example, but I have no opinion about this make and model.

Z-S1079-1.jpg

https://store.rc4wd.com/RC4WD-110-Warn-95cti-Winch_p_3734.html

Specifications:
  • Cast Aluminum Case
  • Synthetic Winch Rope
  • Voltage: 6v to 11.1v
  • Can operate on 3 Cell Lipo
  • 3ft/.9M Rope Pre-Installed
  • Load Limits: Dead Lift 6.6lbs/3kgs
  • Load Limits: Rolling Drag 9lbs/4.1kgs
  • Length: 2.9in / 73.68mm
  • Total Width: 1.25in / 31.75mm
  • Height: 1.31in / 33.56mm
  • Weight: 2.1oz / 60g
 

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  • #28
jim hardy
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Where i live every yard sale and junkshop has a basket full of old battery powered electric drills with dead or no batteries for one or two dollars each.
I buy them just to salvage their twenty dollar keyless chucks but that's a digression.

I took one apart just to see how it works and found a brushed PM motor with high quality planetary reduction gearset.
For the miniscule cost i'd acquire a few junk battery drills and see whether they'll run on your peltier power. A 7.2 volt might be your best bet and they are not coveted even by junk shoppers so should be dirt cheap.
Replace the variable speed trigger with a pushbutton switch, replace the heavy gear grease with light oil, and you just might have something you're not afraid to abuse. It only has to run a few minutes and spares are cheap.

old jim
 
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For the miniscule cost i'd acquire a few junk battery drills and see whether they'll run on your peltier power. A 7.2 volt might be your best bet and they are not coveted even by junk shoppers so should be dirt cheap. ...

old jim
Might be worth a try, but I'm really getting the sense that those Peltiers won't provide that kind of power. The 12V/5A spec is, I believe, an input power spec to get max heat delta out. When providing a heat delta in, it looks like you will only get ~ 1% of that as output power to drive a motor. A small toy motor designed to run on a 1.5V battery might be about all one could expect to power?
 
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  • #30
jim hardy
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I never experimented with one of those Peltier devices. Looks like you're right, efficiency is not much.
Found this tutorial on using them . It explains sizing of the heatsinks.
https://thermal.ferrotec.com/technology/thermoelectric-reference-guide/thermalref13/

Here's the most powerful TEG modules i could find but they're cost prohibitive. And work at dangerous temperatures.
https://thermoelectric-generator.com/teg-cascade-800c-hot-side-thermoelectric-power-modules/

you might write the company and see if they'd donate a blemished 'factory second' for your project . It'd be good advertising for them.

I can see showmanship potential - a TEG module on a huge block of ice with a giant Fresnel lens above at High Noon !
 
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  • #31
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Hi!,
I just wanted to give you an update as a mean to say thank you because all your ideas were extremely helpful! I passed Thermodynamics thanks to this project, and I ended up working on it alone so the last few semester weeks were hell hahaha. Anyway, just in case any other student finds this thread and for everyone that has shared their opinion, the peltier efficiency was around 5%, I had to use dry ice in a aluminum container on top of a heat dissipator attached to the cold side of the peltier, and applied a temperature around 300oC to the hot side, above that temperature they will surely pop. I used thermal insulation tape on the peltier sides to protect the internal glue from overheating and keep the heat transfer on the two main faces. Ended up getting like 3-4 V max with a 500 mA current, none of the motors I had ordered worked with such a small current so I went to an electric shop and bought an RC car motor that had its own small plastic gearing case and attached a plastic nylon reel to it to tow a small 100g laser cut car, I did not even try to go for the prize cause this was the only working design out of 3 failed attemps and I was fed up and sleep deprived on the presentation, but everything went well and just by reaching the top of the slope where the competition was held you had a full mark on your project, at the end no one really tried to win the competition cause it was much harder that expected and everyone was so done with this project, but I'm happy because I feel like I learned a lot.
Anyway, I just wanted to say thank you everyone for your opinions, here are some pictures of the parts I mentioned above.

https://ibb.co/deSbgU
https://ibb.co/kbLU1U
https://ibb.co/iBAq89
 
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  • #32
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Thanks for the update. That tower of dry ice and large heat sink is impressive! I think you did very well to get 1~2 Watts out of that Peltier. I'm sure you learned a lot, as you were originally thinking of tens of watts and much larger motors.

These Peltiers seem so attractive at first glance: temperature delta in, electricity out! No moving parts! Small and light! How elegant!

But in practice, getting meaningful power out becomes quite involved. Congratulations on getting full marks on this!

I remember the first time I played around with a Peltier at a hobby level. I held it pinched between my fingers, applied power, and was thrilled that I immediately felt heat on one side, and cold on the other. That thrill dissipated as fast as the heat dissipated from one side to another through the junctions, and it just turned into a heater (in a second or two)! Yes, it takes a lot of attention to heat transfer on both sides to attain significant results.
 
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