3 Battery Generating System

[Turion]

Info

You got it. Because some of the energy input into the motor is cycled back to the battery, charging it.

[bistander]

Just doesn't seem right

...

I run two boosts in parallel off the battery and the output is a bit over 93% of the input. It is set to about 26 volts so the motor is seeing about 12. I am using the modified Matt motor so although there are some losses, I get extended run times with just these three components. By this I mean the motor runs longer than it would off just the battery. ...

YOU are looking at the light as your load. I am looking at the motor as mine. It makes a difference.
...

So you have three components. One battery and two boosts (converters, I assume). The motor is the load.
You get 93% of battery energy out of the converters (to the motor). And you claim the motor runs longer with 93% of battery energy than it does on 100% of battery energy.

[Turion]

Lol

Bi,
I know all that. Just wanted to see you get all wound up again and show us all you know. But it was ALSO to point out that there are DIFFERENT components in this system. Why that is important will be clear in a moment.

As to your data...

All I can talk about is what I see on MY bench with MY setup. It isn’t up and running now, so I am going from memory and many, many, MANY runs are kind of mixed together in my head and I am on the road to AZ to see my kids, so don’t have access to any of my lab books and notes, so this is a general statement.

I run two boosts in parallel off the battery and the output is a bit over 93% of the input. It is set to about 26 volts so the motor is seeing about 12. I am using the modified Matt motor so although there are some losses, I get extended run times with just these three components. By this I mean the motor runs longer than it would off just the battery. I have a second Matt motor as generator and used a light as a load. The output of the generator goes through the light to the battery. The light flashes on and off rapidly. The battery runs THAT setup far longer than just the three basic pieces, which is STILL longer than just the motor connected to the battery, which is why I posted it.

YOU are looking at the light as your load. I am looking at the motor as mine. It makes a difference.

You have different components. You will get different results.

[bistander]

Previous post continued

Turion,

You speak often of "reusing" energy. About the only way of which I am aware can also use the car as an example. The input energy is in the fuel and output energy is the work done moving the car; the difference between the two amounts of energy is the waste heat coming out the exhaust and radiator. In the winter, some of that waste heat is diverted from the radiator to the cabin heating blowers. Heating the cabin and occupants is useful work so should be included in the system output for efficiency calculation. Such a scheme is often called cogeneration when used on larger scale with generation stations. In the car, it is a small fraction of total energy so is neglected in the mpg numbers.

bi

[bistander]

system

Hi turion,

that is one way to lose the fight, conservation of energy would say "energy was transformed" from battery>module>motor>gen>module>load all with less than 100% eff. resulting in "heating of the environment".

Thank you ricards. Very good.

Turion,

(input) battery>module>motor>gen>module>load (output)

Energy is put into the system (from the outside world) by the battery. The load resistor represents energy delivered from the system to the outside world. Output of a system for efficiency is that power or energy doing useful or desired work outside the system. In this case we used a resistor for convenience so the work done was heating of my workshop. The load resistor could have been a lamp, or a fan, or a pump, or a coffee maker.

Some time ago I explained this to you by saying to put the system in a box. There are 3 ports. Input, output, and waste. Everything going on inside the box doesn't count in the efficiency calculation. Those are just internal processes.

Example. Efficiency of a car. Usually in miles per gallon. mi/gal, or mpg. Miles is short for work done to move vehicle a distance and knowing car's mass, rolling resistance and shape (for aero drag) could be converted into ft.lbf. (units of energy). Gallons represent input energy and easily converted to units of energy, BTU, knowing the type of fuel.

So car efficiency is output (work done moving a distance) divided by input (BTUs contained in the fuel used). One does not add up the engine output, the transmission output, the differential output, etc to get total power or energy converted to figure efficiency. Those are internal system intermediate conversions which do no useful work on the outside world.

bi

[ricards]

bi,
Your data would have been much more favorable had you used a pulse motor, but lets take a look at what actually went on in the circuit.

According to your data...
How many watt hours were consumed by the first boost module?
How many watt hours were consumed by the motor?
How many watt hours were consumed by the second boost module
How many watt hours were consumed by the "load"?
All FOUR of the above were run by the system were they not? So aren't all FOUR of these devices the "actual" load?

What is your total power consumption for the time you ran the system? If you are only going to look at what was used to run the "load" in the diagram, it was a total failure as a system. But what if this little circuit was only to show you the power that is available? What if there was a better way to utilize that power to run the load.

Hi turion,

that is one way to lose the fight, conservation of energy would say "energy was transformed" from battery>module>motor>gen>module>load all with less than 100% eff. resulting in "heating of the environment".

[Turion]

Da

bi,
Your data would have been much more favorable had you used a pulse motor, but lets take a look at what actually went on in the circuit.

According to your data...
How many watt hours were consumed by the first boost module?
How many watt hours were consumed by the motor?
How many watt hours were consumed by the second boost module
How many watt hours were consumed by the "load"?
All FOUR of the above were run by the system were they not? So aren't all FOUR of these devices the "actual" load?

What is your total power consumption for the time you ran the system? If you are only going to look at what was used to run the "load" in the diagram, it was a total failure as a system. But what if this little circuit was only to show you the power that is available? What if there was a better way to utilize that power to run the load.

[Turion]

Data

Your data would have been much more favorable had you used a pulse motor, but lets take a look at what actually went on in the circuit.

According to your data...
How many watt hours were consumed by the first boost module?
How many watt hours were consumed by the motor?
How many watt hours were consumed by the second boost module
How many watt hours were consumed by the "load"?
All FOUR of the above were run by the system were they not? So aren't all FOUR of these devices the "actual" load?

What is your total power consumption for the time you ran the system? If you are only going to look at what was used to run the "load" in the diagram, it was a total failure as a system. But what if this little circuit was only to show you the power that is available? What if there was a better way to utilize that power to run the load.

[bistander]

Battery

I used a battery for the system test. I only used the power supply to check out the motor and generator before wiring them into the circuit.

I don't buy into "low lenz". Give me good old efficiency. I think my little DC generator is as, or more, efficient than the machines I've seen used by 3BGS builders.

bi

[hherby]

Re: so it would seem

The one battery circuit was intended to use a low lenz generator that will not drag the motor down when a load is placed on it. Turion pointed out a few possibilities besides his own design such as MrAngusWangus, an interference generator similar to Al Francours design and another who's name escapes me at the moment that used disc shaped neos allowed to spin horizontally as it passes a generator coil where the back mmf would make the magnet spin instead of dragging down the rotor. There are more options like flux switching generators or kromrey convertors, g-field generators, Tewari RLG, homopolar generators and most likely others we have never heard about.

I don't know what to say about the difference between using a battery or a power supply as the source without having your setup on my bench. The experiment was intended for a battery to be used as the power source.

Another thing I have encountered is problems with boost converters that are unable to deliver current on higher loads. Depending on the controller chip and circuit used in the device, it may not be slope compensated for duty cycles above 50% causing instability like the UC3845 without slope compensation circuitry in the converters I have. The other problem is the small inductor cores which are used. These small torroid cores may be saturating at higher duty cycles or being current limited when approaching the saturation point. A serious load will require seriously powerful off the shelf boost converters or ones designed for optimal performance under the specific conditions you want them to perform under. There are a lot of parameters to consider in a design. Input voltage, output voltage, output current, voltage ripple, inductor current ripple, low DCR windings, low ESR caps, core power ratings to accommodate peak inductor current without saturating, using synchronous rectification vs schottkey diodes, low Rds on mosfets, impedance matching to the load etc. etc. etc.... Lots of research to do in boost convertor design let alone low lenz generator design. So much to do, so little time...

Cheers,
Alex

[bistander]

so it would seem

Ok, so I take it your motor-generator draws more amps when you put a load on the output?

Cheers,
Alex

Yes, I would think so, but attempting to increase the load on the output only increased the input power and did not really increase measurable output power. I guess it just de-tuned the system (made it less efficient) and/or increased instability.

If you notice the photos, my motor and generator are identical conventional brush/commutator DC machines shaft coupled. When run from a conventional power supply, increasing the load power does increase the input power approximately proportionally.

Regards,

bi

[hherby]

Re: Analysis

I recall attempting larger load (more output power) but input power increased substantially and some of the components were overloading or becoming unstable.

Regards,

bi

Ok, so I take it your motor-generator draws more amps when you put a load on the output?

Cheers,
Alex

[bistander]

Battery measurements

...
How do we measure exactly what is going into/coming out of the battery when we are running between positive potentials?
...

Cheers,
Alex

Simple. Put the wattmeter directly on the battery terminals and all other connections on the other side of the wattmeter. You can verify that with a scope also probed on battery terminals.

[bistander]

Analysis

Hi hherby,

Thanks for chiming in. No, I don't have those battery resting (no-load or open circuit, I assume you mean) voltage readings.

Member dragon had a good take on it here:

To me it looks like the battery is supplying 12.2 volts at 4.47 amps to the boost, 54.53 watts. The motor sees 20.6 volts at 2.18 amps or 44.9 watts. Around 83% efficiency. The 6.78 amp reading is deceptive because that is the combined current in that loop ( 4.47 + 2.18 = 6.65 amps ).

The output of the generator is 11.7 watts and the output of the 2nd boost is 10.57 watts, there we see around 90% efficiency. The battery is clamping the voltage at 12.2 with a .36 amp return or around 4.4 watts going back to the battery and 6.58 watts being dissipated by the load or 10.98 watts total.

He was using test 3 data, IIRC.

If you compare tests 3 and 4, you see input power of 54 and 41 watts for essentially the same output power to load resistor. Obviously everything was warmer when I took data readings in test 4 after running for three hours.

I recall attempting larger load (more output power) but input power increased substantially and some of the components were overloading or becoming unstable.

Regards,

bi

[hherby]

I ran that system for 3 hours. That took 333 watt hours from the battery. If I would have run a 6.1 watt load directly from the battery, it would have run for 54.6 hours.

And with a converter between the battery and motor, those pulses are blocked.

What's your opinion of the real data?

bi

Hi Bi,
Just wondering if you remember the pre-test resting voltage of the battery and the resting voltage of the battery after the test?

Matt mentioned in a post somewhere that the pulses from the motor are being captured by the output capacitors of the boost converter thereby decreasing the load on the battery a certain amount.

My thoughts on your data.
First, thanks for sharing.
There will be a certain amount of overhead to run the motor-generator.
The 50 ohm load was not letting enough current through to help overcome the overhead. The system was not in balance. Example, a load with a resistance of 3.72 ohm would allow 4.88 amps to flow to the battery which would balance with the output to boost 1 (assuming the motor-generator does not draw more current under an increased load). At that point the voltage on the battery will remain constant as the system would be in balance. For a little more clarity, lets move the connection of the second boost converter negative from the battery negative pole to the negative input to boost converter 1. Now place an amp meter between the battery negative and boost converter 1 (and now 2) negative. When the system is in balance, you will be running the load for free (in conventional terms) and the reading on that amp meter between the battery negative and the boost converter negative should read zero.

From my tests that Dave mentioned in post #4265, the meters are not showing the whole picture. There is less load on the battery than what appears to be drawn by the boost converter when running the load between two positive potentials. When I ran my tests the battery resting voltage returned to the pre-test voltage level or higher.

In this one battery circuit, the output of the boost converter goes to the positive of the motor and the negative of the motor goes back to the battery positive. The motor is running between two positive potentials. It is not going back to the battery negative so it will not be contributing to destroying the dipole of the battery. So what is happening with the power that was run through the motor and back to the battery positive? Since it is not connected to ground, it is a separate dc loop is it not?

How do we measure exactly what is going into/coming out of the battery when we are running between positive potentials? I'm not sure which is why I am asking. I suspect when running the load between two positive potentials in this setup, the energy used by the boost converter is to simply create a higher potential than the battery.
Thoughts anyone?


Cheers,
Alex