Introduction, Max in Ontario Canada

Posted by: @madmaxx1313

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Hello, As a bit of an intro I am a science teacher, Biology specialty but decent in physics and chemistry, in the north woods of Ontario Canada.  My interests range from art and fishing to DIY clean energy and DIY batteries.  I mainly joined hoping to get some help with practical projects for students.  For example, though I know readily the science and how to make triboelectric generators how would one store the energy in a battery for use?  One of the most frequent questions I get is "but what use is it or how do we use it?" so I try to have a series of projects that not only demonstrate the underlying principles but also how to translate that into practical use.

Welcome to the forum. How far north, I am in Elliot Lake. I recently put in a solar system for my RV, which I am now selling, so I have a bit of practical experience.

By DIY batteries, do you mean assembling either the round cells or the RAW cells into a battery?

I was just watching Will Prowse talking about the latest news on Raw cells and he says you might be better off with 'server rack' grade cells as they come with a high-grade BMS and are higher quality for a very small price increase. As you no doubt know, Will is extremely knowledgeable, so when he speaks I listen.

I am not sure what you are looking for when you say

how would one store the energy in a battery for use? 

Maybe start a new topic in the appropriate forum/sub-forum as this is the introduction forum.

Posted by: @madmaxx1313

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triboelectric generators (TG)

Welcome to the forum. 

@zander, I think the key word he used might help.  Although I have to admit even after reading the explanation, I wasn't much better off.  I think its the ability to scavenge very small quantities of energy from the environment.  The examples it mentioned were what sounded like (1) static electricity by rubbing things together.  I wonder if these might fall under that TG category... (2) piezoelectric transducers in shoes and scavenge electricity while hiking.  (3) Aren't there thermal scavengers that can turn body heat into power for like a pace-maker?  (4) Scavenging power from sound waves by using a microphone.  (5) Scavenging energy from the radio waves floating all around us to power things.

... at least those I've heard about over the years that sound like this TG.  

Posted by: @madmaxx1313

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For example, though I know readily the science and how to make triboelectric generators how would one store the energy in a battery for use?

I can copy cookbook instructions, but hardware electronics are mostly a mystery to me, but @inst-tech and @davee will hopefully be far more useful to you.  But have you seen any of these...

https://en.wikipedia.org/wiki/Joule_thief - Search on Joule Thief and you'll get hundreds of circuits, experiments and uses.

https://www.instructables.com/Piezoelectric-Shoes-Charge-Your-Mobile-Device-by-W/

https://blog.piezo.com/can-piezos-power-my-cell-phone-by-walking

@inq Yes I have heard of some of those.

Hi @madmaxx1313,

  I can't recall anyone trying to use a triboelectric generation mechanism to generate power to charge a battery ... though please note I am not claiming any expertise in this area, so you might want to try further searching.

It is possible that the amount of electricity generated is too small compared to the amount of mechanical of work required to generate a usual amount of electrical charge, for it to be considered a practical solution to a 'real' problem or need ... i.e. it may too inefficient, with the majority of energy input simply being converted to heat. (I haven't checked or researched this suggestion in any way .. it is merely a suggestion to consider.)

Of course, as a teacher you may well have access to a Van de Graff generator or similar ... but note they generate a very high voltage at a tiny current ... so the amount of power (Watts = Voltage X Current) is small, and furthermore, it is at a high voltage, which needs to be converted to a low voltage (say 1-5V), at a more substantial current, to charge a typical cell.

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The approaches of 'scavenging' energy for the environment I have heard of include:

• piezoelectric .. using vibration to mechanically distort a suitable component/material
• electromagnetic generator .. typically based on vibration moving a coil and a magnet, with respect to each other
• receiving radio transmissions and rectifying the signals to produce a direct current
• Seebeck effect .. generation of electrical current at a junction of two dissimilar conductors that are held at different temperatures

In all of these cases, the amount of environmental energy is usually low, although there can be special cases in which vibrational energy is much higher due to the movement of nearby objects, such as a fluid passing through a pipe, or a mechanical machine operating nearby.

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In addition, human interactions with something in the environment may be sufficient to generate a useful electrical current. For example, a switch has been developed, which generates sufficient electrcal power when it is operated, to generate and send a local radio message, to indicate the switch was operated.

That is, it is proposed that this type of room light switch does not actually need to wired to a power source ... it might be simply fixed to a convenient wall, and the room light power switching would be performed by a centralised remote unit, greatly simplifying the wiring needed for the building.

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For all the scavenging units I can recall, the electrical energy generated is small .. a few milliWatts or less, and the power levels often continuously vary with time, which makes electronic circuits capable of efficiently capturing this energy somewhat specialised, and typically a research topic (University or equivalent level) in their own right. That is not to say, you cannot find, design and build a useful unit, but you may have to do a considerable amount of careful research.

I wish you luck with your research and project ... I am sorry, but I am not in a position to be able to offer a neat solution to your question.

Best wishes, Dave

Hi @madmaxx1313, Yes, as a practical matter, I have to agree with @davee on the use of triboelectric sources for salvaging energy and storing it for consumption of devices that require power over say 100 mW (milli-watts). However, salvaging energy from used up (dead) batteries would be a practical solution that your students could use to charge a cell phone battery. an example would be in the following link: https://www.instructables.com/Joule-Thief-Low-Voltage-Battery-Charger/

Also, as @davee mentioned, using the Seebeck principal, (ie Thermocouples), are used  to provide a milli-volt (mV) input to a amplifier in gas furnaces to open/close solenoid gas valves. see link: https://eevblog.com/forum/projects/thermocouple-millivolt-gas-valves-how-do-they-work/

While there are many such devices used in industrial and manufacturing, NASA, and military use, they are not commercially available to the public.. but the principals and theory are easy enough to discover...lol 

Good luck with your project research, and keep the creative juices flowing in those young people.

Kind regards,

LouisR

Well folks, the raindrop generator is supposed to have an energy density of approximately 700W/m^2, half to 3/4 of what is produced by solar panels so the "it's too little" to be of use is in error.  Might I suggest actually watching the video's and reading the science it's based on.

Posted by: @madmaxx1313

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Might I suggest actually watching the video's and reading the science it's based on.

Might I suggest you actually look at the links I supplied instead of asking the same question over an over.  The third link clearly shows a method for storing small spikes of energy in a battery!

Posted by: @madmaxx1313

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Well folks, the raindrop generator is supposed to have an energy density of approximately 700W/m^2, half to 3/4 of what is produced by solar panels so the "it's too little" to be of use is in error.  Might I suggest actually watching the video's and reading the science it's based on.

Maybe I am losing it but each of my solar panels is very close to a M^2 and are rated for 200W. I would love to have the solar panel you are referring to with 1,400W to 933W.

If you can get 700W from a M^2 compared to the 200W of an equivalent sized solar panel, I think we can go a long way to solving the world's energy problems, especially in the poorer parts of the world. We could get rid of a lot of carbon in the atmosphere in a very short time.

Do you have a patent?

Hi @madmaxx1313,

  Sorry, but as I said, I was only commenting on what I was aware of, which include systems which have been developed to charge small batteries for useful purposes.

Only researchers in a particular field are able to cover latest developments etc., so perhaps you need to contact those working in the particular field if you want useful answers in a specialised field like this one.

As I said,"please note I am not claiming any expertise in this area, so you might want to try further searching." And I obviously had not come across "raindrop generation" before.

I haven't done any proper checks but a quick Google found https://www.sciencedirect.com/science/article/abs/pii/S2211285522005213

The abstract of which includes "the ultra-high instantaneous peak output power (765 W/m2)" ... but doesn't define 'instantaneous" ... it might be a femtosecond or less! To charge a 'useful' battery you need a low voltage, relatively steady, moderate current for a sustained period of time.

If the 'peak power' involves, very short, high voltage spikes, then they will be a real challenge to convert into a useful power source. Knowing an instantaneous power level, without knowing its duration, is meaningless for assessing its capability of charging a battery or doing a useful amount of work.

But since, I don't have access to the whole paper, sorry, I can't add any further useful comments at this stage.

So please continue your research and I wish you success. Best wishes, Dave

@inq Thanks, I had looked at that and so far it is the only one that shows some promise unfortunately there was far more "can'ts and not worth it's" being put forward which I was responding to.  Everything is impossible until it is done.

@madmaxx1313,

You have supplied no/none/nada links in this thread and you should have no expectations that anyone reading this thread knows anything about your other thread. You referenced two videos in that thread.  I watched the first one completely.  It sounds reputable but makes no such claims as 700W/sq-m.  In fact, it makes no claims of power output whatsoever.  The second one... is a Snake Oil charmer that makes money off his YT channel converting PVC pipe into a wind generators.  He's an interesting personality... but I would never use him as a reference for any real science.  I only watched the first ten seconds. 

You say you are new to Physics.  Well... you should be able to work out the following  Conservation of Energy problem. 

From your first video... 100 micro-liters released from 15 cm.  Doing the Potential Energy calculation...

• 100 μl => 0.0001 Kg => 0.000981 N
• 15 cm = 0.15 m
• P.E. = 0.00014715 N-m = 0.00014715 Joule
• Let's optimistically say they're dropping one drop/second.
• 0.00014715 Joule/second = 0.00014715 W
• Their test sample appears to be about 2 sq-cm
• Thus if we again assume 100% conversion of P.E. into electricity (which is impossible) they are making about 0.74 W/sq-m

They present no evidence that this can be scaled up by dropping more water (though they try to fool the audience by showing waves hitting rocks) or by dropping it faster or dropping it from higher.  They are obviously going to show the best rate they can.  The material presented obviously has a minimum reset time.  Just like a Piezo electric material... it only works during the transitions from pressure to/from no pressure.  It must have a finite reset time.  You can't just keep a pressure applied and expect free-electricity.  

Posted by: @madmaxx1313

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Everything is impossible until it is done.

I would love to be proven wrong, and have a 1 sq-meter panel that makes 700 watts. but the science isn't there.  The laws of physics don't lie.  If you think one of those video authors has stumbled on some undiscovered new laws of physics... I have no words (that I can say here).  Now if you would actually supply a link to a formal paper showing this 700 W/sq-m, I might actually entertain reading it.

Otherwise, I'll hold my breath waiting for Cold-Fusion.

@inq I had a gut feeling the 700W/m^2 was supposed to be 700mW/m^2. Looks like a case of the misplaced m.