One type is rarely used, so I will ignore it. The other two are "A" circuit and "B" circuit. This page explains the difference. https://alternatorparts.com/difference-between-a-b-circuit-regulator.html

I think that the easiest way to accomplish both functions with an Si series is to simply remove the original voltage regulator, and bring the connections to the brushes outside the alternator case. This would allow easy connection of a switch that would allow a manual control circuit for welding, or when the switch is flipped, connection to an external voltage regulator for charging. Many ford and dodge vehicles had external regulators even into the 1980s, possibly later. I looked one up for a dodge earlier and found them to be in the neighborhood of $15. That is cheaper than a

Perhaps this info will be useful to someone. It is a route I am likely to take with my project, though I have an additional twist I want to try with mine. ]]>

In terms of more familiar ballistic energy units, that's 14,571 ft-lbs – about the same as a modern .50 BMG. That's a cool coincidence. Of course, a trebuchet stone ball is much more massive, moves slower, and will carry a wallop more in momentum. Don't want to get hit by either!

Makes one appreciate modern technology.

It is really interesting to look at 'ball throwers' over time. There seems to be a sweet spot for 25 pound projectiles. We saw that the best medieval technology from the 1500s using gravity can throw such a projectile at about 100 mph. Fast forward to the 1800s and with 3lbs of blackpowder (ie chemical energy) a cannon like the Parrott Rifle can throw a 24 lb projectile to 1100 mph.

Fast forward to today and an electromagnetic railgun can throw a 24 lb projectile at 4600 mph.

http://www.popularmechanics.com/military/weapons/a21174/navy-electromagnetic-railgun/

]]>

So how much energy does this thing produce? It hurls ~30 lb balls at 121 mph (13.5 kg @ 54.1 m/s).In terms of more familiar ballistic energy units, that's 14,571 ft-lbs – about the same as a modern .50 BMG. That's a cool coincidence. Of course, a trebuchet stone ball is much more massive, moves slower, and will carry a wallop more in momentum. Don't want to get hit by either!

...

So we can use that as a basis of its output energy using the following formula:

Kinetic Energy = 1/2*mass*velocity^{2}= 1/2 * 13.5 kg * (54.1 m/s)^{2}= 19,756 Joules = 5.49 Watt-Hours

Quote

So with the proper escapement and charging arrangement this should be able to charge 6 AA rechargeable batteries!Makes one appreciate modern technology. A little $100-ish Goal Zero kit can do the same job, fits into a backpack, and doesn't need a half-dozen serfs to turn the hamster wheels.]]>

Using falling weight devices (gravity) has been around for centuries. Example: The "treadwheel" crane was used during Roman times and the Middle Ages to lift and move very heavy loads. It made use of the weight of people walking inside a large wheel (think their body weight and gravity), turning a spindle and winding a rope, using gravity and mechanical advantage to lift stone blocks for castles and cathedrals. Don't forget Middle Ages "artillery": the Trebuchet, A weight driven" catapult" that could throw hundreds of pounds, hundreds of yards.

I don't see why creative thinking couldn't use gravity to power electrical devices.

You are onto something here.

The largest trebuchet in the world (actually the largest siege weapon period) is the one at Warwick Castle. It holds the world record for energy in siege engines launching projectiles. It uses a crew of six in giant 'hamster wheels' to set the counterweight (crew of four to charge and another two to unwind ropes so it doesn't self destruct).

It is likely the most substantial human power device ever weighing 50,000 lbs with its arm rising to 59 feet above the ground. Amazing machine.

So how much energy does this thing produce? It hurls ~30 lb balls at 121 mph (13.5 kg @ 54.1 m/s).

So we can use that as a basis of its output energy using the following formula:

Kinetic Energy = 1/2*mass*velocity

However, this is the energy that it outputs in throwing a ball. This is quite an inefficient process as you are accelerating a large, heavy arm, not just the projectile itself. So let's calculate the energy it actually stores in its counterweight.

From the published materials

I estimate this to be 6.1 feet. So the amount of energy stored is:

Potential Energy = 13,440 lbs * 6.1 feet * 0.000376 Watt-Hour/foot-lb = 30.8 Watt-Hours

So with the proper escapement and charging arrangement this should be able to charge 6 AA rechargeable batteries!]]>

This video is great at explaining it:https://m.youtube.com/watch?v=SScpJMsCm9c

Here is a practical, working hybrid design. :

https://youtube.com/watch?v=xv1lQA-tnwo

https://youtube.com/watch?v=zLoQIAWmQbM

https://youtube.com/watch?v=8wX4WtOHFZE

]]>

PLEASE, check my numbers... I babble a lot....

Turning generators with moving water, caused by the sun (natural, and artificially induced means to move water to a higher location, or from a pressurized container.) Power can be constant and regulated. Most naturally occurring cases of water in a high gravity location have already been exploited.

Where tanks can be positioned at significant differences in altitude (i.e. 100'+) water pumped by windmill to the higher tank can bank the energy (serve as a battery) for later expenditure by turning a generator when dropped again thru a turbine. Think outside the box… Can you modify a turbocharger from a car to serve as the driving turbine in a micro-hydro generator?

Factors:

1kw = 1.3 hp

Water flow in cubic feet/second x height difference in feet divided by 8.8 = hp

1 cubic foot = 7.48 gallon

Assume two 10,000 gallon tank, one 100' higher than the other. To generate 1kw of power

1kw = 1.3hp = flow/second x 100 / 8.8

1.3 x 8.8 = flow x 100

11.44 = flow x 100

11.44 / 100 = flow

.1144 cubic feet = flow

.1144 cubic feet = .856 gallon/second

10,000 gallon tank / .856 = 11,682 seconds / 60 / 60 = 3.24 kilowatthours for this "battery".

Each of the above tanks is only about the size of a modest “above ground” swimming pool. Consider a well where the water level is more than 100 feet below the surface. A small windmill could easily during the day fill the pool, providing the evenings power for light and electronics.

Hi fred.greek. We can use the 0.000376 W-H per lb per foot number calculated above to quickly check your thought. A gallon of water weighs 8.34 lbs so:

Potential Energy = 10,000 gallons * 8.34 lbs/gal * 100 feet * 0.000376 Watt-Hour/foot-lb = 3,136 Watt-Hour or 3.1 KWH.

This is really close to the 3.2 KWH you calculated so it looks good to go. The slight difference is probably rounding in using 1.3 hp per kilowatt vs 1.341 hp per kilowatt.

]]>

and the question was not about the gravity light so that portion of your post is still puzzling to me. Concrete blocks weigh 28 pounds and were one, among many things that I would consider using as a weight and raising to a much higher level than you assume.

Ah, i see where that could have been confusing. if you look through the responses you will see this one from kckndrgn where there was a question of how many times a gravity light would need to be reset to charge a battery pack:

For the OP, is this what you are looking for?

http://deciwatt.org/

GravityLight™ is an innovative device that generates light from gravity.

It takes only 3 seconds to lift the weight that powers GravityLight creating 25 minutes of light on its descent.

It can be used over and over again with no running costsWhile the main purpose of the gravity light is, light, it could easily be set to charge batteries. The problem, how many times would the system have to be reset to get a full charge on the batteries?

Might be good for keeping a charge on already charged batteries so they are ready for use.

I was offering an answer to that question.

But, here's a challenge for you, since you say you want to collaborate - How would you make this work? Say you got caught in a flood, and all you could salvage was a DC motor and someone you cared about needed some small, but life-sustaining, battery operated, machine to keep running for an indeterminate period?

Well, that isnt much to go on from a scenario point of view. How much power are we talking? I definitely wouldnt use gravity storage as an intermediate step as it would be much more efficient to charge the battery directly for example with a hand crank.]]>

mangyhyena

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Why can't a gravity powered generator work?

« on: June 16, 2012, 07:31:08 PM »

and the question was not about the gravity light so that portion of your post is still puzzling to me. Concrete blocks weigh 28 pounds and were one, among many things that I would consider using as a weight and raising to a much higher level than you assume.

But, here's a challenge for you, since you say you want to collaborate - How would you make this work? Say you got caught in a flood, and all you could salvage was a DC motor and someone you cared about needed some small, but life-sustaining, battery operated, machine to keep running for an indeterminate period?]]>

PE = 0.4536 kg * 0.3048 m * 9.8 m/s^{2}= 1.357 kg m^{2}/s^{2}= 1.3549 Joules

Oops. Saw a typo. Sorry for any confusion. This should read:

PE = 0.4536 kg * 0.3048 m * 9.8 m/s

you are looking for ways to make it seem as though this can't work vs collaborating on ways to make it seem that it can work.

Not at all.

So, again, the question was: Why can't it work" and the answer is "It can work, but it may be inconvenient".

I would put it another way. You can use gravity to store energy but it is useful in only a very small number of very specialized cases. Man moveable masses are only practical for powering things of very low wattage, like a few LEDs. As others pointed out, extremely large masses do have use for storing excess power plant energy. Examples would be water pumped storage or the new ARES rail system which uses train cars and regenerative braking technology.

Still not sure about your numbers, but let's assume that they are correct...Still, something seems a little off in all this and my hunch is that there is a mismatch in units somewhere

No need to assume as it is easy enough to verify. To keep it simple we can use the SI system units and just convert Joules to Watt Hours at the end.

Potential Energy of hanging weight = Mass X Height X gravitational constant

Mass = 1 pound = 0.4536 kilograms

Height = 1 foot = 0.3048 meters

Gravitation constant = g = 9.8 meter / seconds

Therefore potential energy of 1 lb mass at 1 foot is:

PE = 0.4536 kg * 0.3048 m * 9.8 m/s

1 Watt-Hour = 3600 Joules so:

1.3549 Joules/(3600 J/W-H) = 0.000376 W-H

This is very close to what I calculated before. Originally I used the imperial system and used 32 f/s

Net, I see no error in my calculation.

You suggest lifting a 27# weight 7' in the air? Why? Why not lift our 27# weight 70' in the air?

kckndrgn asked the specific question of how many times the deciwatt gravitylight would need to be reset. If you look at the specs, you will see that there are maximum design limits set by the manufacturer. One is a maximum weight of 27 lbs. Another is a maximum height of about 7 feet. Why does it have these limits? There are several probable reasons on which we can speculate:

One is that the device uses an electrical vs. mechanical escapement. Specifically, it is the LED circuit itself which slows the drop of the weight. This is actually quite clever as it keeps the mechanism very simple. Despite how much weight you put in the device, it falls at about the same rate and maintains about the same voltage. What changes is the current flowing through it. Eventually this current will rise to the point where the circuit can't handle it. If it is fused, it will blow. Otherwise it goes *poof*.

Another issue with the weight is the gears. The gears are plastic. This has manufacturing and performance advantages (esp. not needing lubrication). But it also means the teeth will break if over stressed. The manufacturer made use of a planetary gear system to push the limit of this. This setup allows multiple teeth to be engaged with the main gear splitting the force among them. But again you can only go so far with such a setup. Similarly, the plastic chain also causes a weight limit as it will stretch or snap if the weight is too great.

Regarding height this is limited in any hanging weight clockwork system like this. Chains have mass. So as the clock runs, the chain moves from one side of the clockwork to the other. This changes the ratio of mass disrupting the movement.

The manufacturer of the gravitylight spent nearly a million dollars optimizing these pieces to come up with the best device they could. It is actually quite impressive piece of engineering. But the real brilliance (Ah, a pun worthy of Carl!) is the LED. It is amazing just how efficient LEDs are at creating light. We have to remember that their creation was worthy of a noble prize in physics.

I've made batteries out of pint mason jars using cheap magnesium fire starter bars and flattened copper pipe as the cathode and anode They use plain old water as the electrolyte. Four of them in series will light a bright LED...practically forever, or at least until the metal is used up.

...

I don't see why creative thinking couldn't use gravity to power electrical devices.

The natural forces within chemical storage are much, much stronger than gravity. Gravity is very weak. Think of it this way. We live on a big rock with a mass of about 6,000,000,000,000,000,000,000,000 Kg. Yet, with just a little thought we can send a tiny current into our muscles and completely overcome the gravity to propel ourselves. Or how easy it is to lift a small magnet off a wood table (gravity only) vs. a metal table (+ magnetism). The number calculated above shows the potential energy per pound per foot. That is what we have to work with in gravity systems. ]]>

As I understand it, electric car battery packs are made up of many individual cells. Individually, they couldn't do much, but together they can power a car. That's what I mean by scaling up a power source. So I wouldn't dismiss low output generating devices. In a SHTF future, we may be running things on potatoes with electrodes stuck in them.

Using falling weight devices (gravity) has been around for centuries. Example: The "treadwheel" crane was used during Roman times and the Middle Ages to lift and move very heavy loads. It made use of the weight of people walking inside a large wheel (think their body weight and gravity), turning a spindle and winding a rope, using gravity and mechanical advantage to lift stone blocks for castles and cathedrals. Don't forget Middle Ages "artillery": the Trebuchet, A weight driven" catapult" that could throw hundreds of pounds, hundreds of yards.

I don't see why creative thinking couldn't use gravity to power electrical devices. ]]>

However, unlike the above example, this is net after escapement gears and dc motor/generator. So we only need to take into account the loss due to charging, which means we need about 12.5 Watt-Hours from this device to charge the 4 AA battery pack. This gives us:

Number of resets = 12.5 Watt-Hours/0.0283 Watt-Hours per set = 441 sets.

Since each set runs for 20 minutes, this means that with one unit it will take 6 days and 3 hours of constant use to charge the 4 battery pack.

Regarding maintaining batteries, the voltage and current specs (2.7 volts, 0.031 Amps) are mighty close to what would be needed to maintain NiMH battery packs. So, it would potentially work for that purpose with something like a 12 hour on/12 hour off pattern."

You anticipated some of my concerns regarding your original response, that I don't think I ever posted. But I still tend to think that you are looking for ways to make it seem as though this can't work vs collaborating on ways to make it seem that it can work.

So, again, the question was: Why can't it work" and the answer is "It can work, but it may be inconvenient".

Still not sure about your numbers, but let's assume that they are correct and see how we can modify the situation to make it more feasible.

You suggest lifting a 27# weight 7' in the air? Why? Why not lift our 27# weight 70' in the air? That suggests we can bring the reps down to 44.

You suggest lifting one 27# object at a time and letting it fall before lifting it again? Why? Why not lift 1 27# object on our device for every 10' of height, or 10 weights running at a time, which would allow it to run, unattended, longer? That suggests we can get down to 4.4 reps pretty easily.

Still, something seems a little off in all this and my hunch is that there is a mismatch in units somewhere. But it seems abundantly clear that while inconvenient, this approach is far from infeasible.

As to the 1,000 # device - I am sure we both agree that those guys are not going to win any awards for efficiency in design, fabrication, or implementation.]]>

They can build a man's idea before he finishes saying it

Maybe Tesla can make a car that runs on a cat and a hairbrush?

I have it on good authority that a cat and hairbrush is the secret behind John Galt's engine.

Speaking of building it, apparently some people have made a hanging weight to electric system. This one uses a heavier weight than above (1000 lbs) but they winch it to a much lower height (4 feet): https://www.youtube.com/watch?v=VsJ7m2VzfRA

They don't appear to be having too much fun trying to keep up with the system. Which reminds me of a favorite saying of one of my old physics teachers: "There is no gravity, the earth just sucks!"]]>

Maybe Tesla can make a car that runs on a cat and a hairbrush?]]>

But you can make the chore more fun by using a rocking chair or make it operate off a heavy ,long swinging pendulum ...

]]>

Had a few minutes so looked into it. They give the stats for it (http://deciwatt.global/technology/) so we can work out how many resets would be required.

Fully loaded and hung (27 lb bag at ~7 feet) it produces 0.085 Watts for 20 minutes (1/3 hour). So it produces 0.0283 Watt-Hours per set (i.e. 0.085 * 1/3 Hours).

However, unlike the above example, this is net after escapement gears and dc motor/generator. So we only need to take into account the loss due to charging, which means we need about 12.5 Watt-Hours from this device to charge the 4 AA battery pack. This gives us:

Number of resets = 12.5 Watt-Hours/0.0283 Watt-Hours per set = 441 sets.

Since each set runs for 20 minutes, this means that with one unit it will take 6 days and 3 hours of constant use to charge the 4 battery pack.

Regarding maintaining batteries, the voltage and current specs (2.7 volts, 0.031 Amps) are mighty close to what would be needed to maintain NiMH battery packs. So, it would potentially work for that purpose with something like a 12 hour on/12 hour off pattern.

But you can make the chore more fun by using a rocking chair or make it operate off a heavy ,long swinging pendulum ...]]>

For the OP, is this what you are looking for?

http://deciwatt.org/

GravityLight™ is an innovative device that generates light from gravity.

It takes only 3 seconds to lift the weight that powers GravityLight creating 25 minutes of light on its descent.

It can be used over and over again with no running costs

While the main purpose of the gravity light is, light, it could easily be set to charge batteries. The problem, how many times would the system have to be reset to get a full charge on the batteries?

Might be good for keeping a charge on already charged batteries so they are ready for use.

Had a few minutes so looked into it. They give the stats for it (http://deciwatt.global/technology/) so we can work out how many resets would be required.

Fully loaded and hung (27 lb bag at ~7 feet) it produces 0.085 Watts for 20 minutes (1/3 hour). So it produces 0.0283 Watt-Hours per set (i.e. 0.085 * 1/3 Hours).

However, unlike the above example, this is net after escapement gears and dc motor/generator. So we only need to take into account the loss due to charging, which means we need about 12.5 Watt-Hours from this device to charge the 4 AA battery pack. This gives us:

Number of resets = 12.5 Watt-Hours/0.0283 Watt-Hours per set = 441 sets.

Since each set runs for 20 minutes, this means that with one unit it will take 6 days and 3 hours of constant use to charge the 4 battery pack.

Regarding maintaining batteries, the voltage and current specs (2.7 volts, 0.031 Amps) are mighty close to what would be needed to maintain NiMH battery packs. So, it would potentially work for that purpose with something like a 12 hour on/12 hour off pattern. ]]>

So I read the responses and followed some links, some bogus, some interesting.

But I think a lot of people are missing something. The original question didn't ask for free power, and it didn't ask for enough power to run a house. It just asked why gravity power can't work.

...

So, it can absolutely be done, relatively easily, as long as we don't get distracted by constraints never posed in the original question.

Welcome to the forum!

The original poster asked about charging a few batteries using gravity. That is a very tough order because gravity is a very weak force compared to the other forces of nature. Here is some quick napkin math (anyone, please feel free to check this).

Let's say we want to charge 4 rechargeable AA batteries with 2.5 Watt-Hour of capacity. That is 10 Watt-Hours total.

In your proposed setup we would use the potential energy of a hanging weight to drive a DC motor into a charger. This would require some sort of escapement as you just can't dump all the energy at once...it needs to charge the battery slowly (over say, about 8 hours). If each of these is 80% efficient (very generous assumption esp. for the escapement) then we will need about 20 Watt-hours; that is 10/(.8X.8X.8 ).

So how much weight do we need for this? It turns out that a 1 lb weight hanging 1 foot off the ground contains the equivalent of .000367 Watt-Hours (using PEgravity = mass*gravitational constant*height). Lets assume that we are going to hang the weight from the tree 12 feet high and that we are going to lift it once every hour for the 8 hours. Then we have:

Weight needed = 20 Watt-hours/(12 feet * 8 lifts* .000367) = 568 lbs.

Net, if the math is correct that is quite an endeavor to charge 4 AA batteries.

]]>

A progressives Elysium dream.

Interesting perspective, the idea isn't abhorrent to you, it's just unworkable.

Depends on who has to pedal.../.]]>

I saw a cable sci-fi show in which were presented people going to the "gym". They spent hours on stationary bikes, before their "shift" was over and they returned "home". It was later revealed as the camera panned out, that the facility was huge, with floors of bikes, hundreds, thousands, tens of thousands. It turns out that this is how the future was being powered, and the labor of millions in producing energy was rewarded with food, shelter and existence.

In a future with depleted, polluting fossil fuels; inadequate alternative energy development due to greedy "Big Energy" and a toxic external environment that may make closed habitation necessary, this could be an alternative. After all, how many educated people does the world really need? Our technological development requirements could be met with a small elite cadre of "smart" people, while the rest of humanity, not engaged in food or commodity production, could "earn their keep" by producing peddle power.

Of course, this is ridiculous and could never support a global population...

A progressives Elysium dream.

Interesting perspective, the idea isn't abhorrent to you, it's just unworkable.]]>