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Need help setting up charging system!

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I'm getting ready to build a light weight trike and need some good advice on what's already going to be an unconvential project. I've got 2 deep cycle 12v Optimas coming. I plan to use them in parallel with a pedal powered generator that will generate more than 48V pretty easily. Yes, I know It's definately outside the box, but I'm going for it. Ideally, I hope to set it up so that the generator charges the batteries and any excess voltage is automatically dumped to the brushed Etek style motor I'm using. Would it be possible to have battery A only engage when charging voltage is reached and battery B only engage when charging voltage is reached for it? Can I do this without a charging system? Am I just dreaming? I know that a slider throttle could do part of this but, I'm hoping to make it all work together seemlessly. Any advice would be grealy appreciated.
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...........need some good advice...... I've got 2 deep cycle 12v Optimas coming.
Hi big,

Don't know if this is good advice, but WTH. Take a discharged Optima and connect it to an automotive alternator. Then belt drive the alternator from a stationary bicycle with the wheel driving the belt. See how long it takes to charge that one battery. Multiply that by 2.

My bet is that it would take you 20 hours to charge those 2 Optimas peddling full time as hard as you can.

Now add in the discharge efficiency of a PbAcid battery and lose 10 to 20% of that energy you just worked so hard to store. Now add in the propulsion motor efficiency and lose another 20 to 30% of that energy you worked so hard to store. See where I'm goin' here?

So, the electric/human hybrid bicycle is a good machine. But use it wisely. Put the human power to the wheel and let the utility company generate the electric energy which you use to charge the battery. Or get a solar cell to charge it for you.

Back to your question about wiring. You cannot discharge 2 batteries in series while charging them in parallel from the same generator. So you will need to use two isolated generators, one for each battery. But these generators can be half size then.

Regards,

major
 

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.....the generator is already putting out DC. So generating say 48v to the batteries would send approximately 20V straight to the motor?.....Any suggestions?
Yes, suggestion for you. Post up a schematic. From what you say, do you have the generator, battery and motor in series? What generator is it? What motor? What controller?

Let's have a look at it :)

major
 

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Hi big,

From reading over the website which you linked, I don't think they really know what they are talking about. I would not trust anything they have posted there and I would not order anything from them. Just my opinion.

OK guys here's what I got for ya. www.hydrogenappliances.com/manta.html has an example of a battery controller I hope to somehow construct. I'll be using a Mars Etek style motor that produces 8hp at 48v. It is rated up to 72v. I believe for only short periods of time though or it may overheat. The generator is a windmill style and produces 12v per every 150 rpms. I'll have 2 12v deep cycle Optimas. I want to modify the battery controller to use the generator obviously. The ideal setup would be as follows: Slider 1 position would just connect the generator to the batteries so as to charge them while in park.
In this position, you will have to sit there for hours pedaling as hard as you can to store enough energy to motivate the vehicle a few thousand yards.

Slider 2 would be generator only to the motor for just pulling out or hopefully reverse if pedalling backwards.
In this position, you will have to pedal very hard to motivate the vehicle very slowly. It will be likely that you are unable to pedal hard enough to overcome a slight incline or maybe even a pebble under a tire. Soon you will find that it is much easier to simply push the vehicle.

slider 3 would engage 1 battery for extra power.
Here you will see a big spark and then a violent lurch as the vehicle quickly comes up to speed. It will only have that one speed to run at. If nothing has broken yet, it will motivate at that speed until you move the slider back off, at which time you will see an even bigger spark and then coast. While it is engaged, you will notice no difference whether you are pedaling or not.

Slider 4 would engage battery 2 for full power.
You will notice that big spark when you disengage position 3 and then another spark when you hit position 4 followed by a lunge and acceleration to a higher single set speed. Again, pedaling will go unnoticed. You will be traveling uncontrolled at a set speed. The only option for any control is to move the slider off of position 4, if possible (it may have welded itself in place due to the arcing). If you do move the slider off position 4, you will notice an even bigger spark and then coast.

This doesn't sound like an acceptable means of transportation to me. But you seem to have you heart set on doing it. So go ahead. You'll learn a lot. But I'm afraid I can't help you anymore that I have already tried, except for this.

Learn about power and energy. Do you know what a horsepower is? I probably don't have all my historical facts correct, but it goes something like this. Mr. Watt was in the mining business a long time ago, in Scotland, I think. The ore needed to be hoisted up out of the mine. They used animal drawn ropes over pulleys with buckets of ore attached to the lower end. Mr. Watt wanted to quantify the work and time required to extract amounts of the ore. He defined "work" as force times distance. And uses a unit of work as a force of one pound over the distance of one foot. Called it a foot pound (ft.lb.).

He was also interested in the rate at which work could be done. He came up with the unit of horsepower abbreviated HP. And set one HP to 550 ft.lb. per second. This is a unit of power. Power is the instantaneous quantity describing the force at the velocity at that instant. As the unit (horsepower) infers, one horse working at a job (moving stuff around) can produce about 1 HP. God did a wonderful design job with the horse. Work wise, maybe not so good with human beings. A fit man is capable of about one seventh of a horsepower, IIRC.

Now power is power, but in different systems, has different units associated with it. So, it is a fact that one horsepower equals 745.7 watts (1 HP = 745.7 W). With a bit of rounding off, a human being is capable of about 100 W of power. And this is a guy working hard at it, not just sitting there waving his hand around.

What is 100 W of power? That is what it takes to make a light bulb shine brightly. You know what a 100 watt light bulb is, don't you? So if you were cranking a generator as hard as you could, it would light up one light bulb. Now, if you did that for one hour, you would have generated 100 watt hours of energy (100 Wh). In my neck of the woods, the utility company charges me about $0.10 per kWh of electricity I use. So, you just spent one hour cranking that generator as hard as you could for $0.01 of electricity. You're telling me that you are willing to work for $0.01 per hour? Dude, my house needs painting :)

That is why back in post #4, I suggested you let the utility company generate the electricity for charging the batteries.

Regards,

major
 

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Hey big,

I guess I can't leave this alone. Did you follow me at all in post #12 about power? Power really doesn't care about gear ratios or voltage. So:
I guess I should have mentioned that I will be pedalling at a 10 to 1 ratio. I don't know if you took that into consideration or not. I just assumed you would expect some ratio gain.
Doesn't make any difference in the power equation.

I should achieve 48v to the motor at what amounts to a leisurely pedalling frequency. Granted it will very well feel like I'm pedalling uphill with the load placed on it. I'm just puzzled as to why that would barely get me anywhere when 48v to the motor achieves around 50 mph.
Again voltage doesn't affect what I had to say about power. But to show you, follow this. You crank or pedal a geneator with all your strength. That produces 1/7th HP or about 100 W. Say that 100 W light bulb is a 10 volt bulb. That means your generator is putting out 10 amps. Power is volts times amps. P = V * I. So now let's change it to a 48 volt light bulb. Then those 100 W would be at 2.08 A. So on a 48 volt load and generator, all a normal fit human would be able to put out is 2.08 amperes. Follow me? That is 100 watts.

Now go to that web site and find the performance curve for the motor. There, I attached it.


Now find the line representing current (or Amps). Follow it down to where it would cross the y-axis (meaning zero torque or load). It doesn't quite get there, but if you were to extend it, it would cross at about 5 to 8 amps, right? That is no-load current on this motor. In other words, it takes 5 to 8 amps at 48 volts just to spin this motor before you can start to do any useful work with it.

Meanwhile, you're pedaling your butt off to generate 2.08 amps. See where I'm going here. Probably not. But I thought I'd give it a shot. Maybe someone else will pick up something from my efforts.

As far as the controller, it clearly points out that contact should be fully disengaged before the next contact is made.
Yeah, I know. It does not affect what I said about it sparking. Anyone who would post that diagram up for public consumption should be severely punished :(

Good luck and don't hurt anyone with that thing.

major
 

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So if everyone is in agreement that a pedal powered generator can produce no more than 100 watts, I guess I'm dead in the water.
I don't know about everyone else. But I haven't seen anyone else chime in.

Even though I've seen multiple examples of them powering 1000W inverters and powering 250W light bulbs. I watched a video just last night of a kid producing 1500 watts to power a huge subwoofer.
Careful of what you see. It may not be real. And don't believe me. Research it and experiment for yourself. Find the truth.

So, major, do me a favor and wash your hands of me.
Done.

I'm not trying to be talked down to or stress you out. I just have ideas on how this could maybe work and was hoping for people much smarter than me to give ways it could work better. Whatever that may be.
Or someone to show you the truth?

Maybe I need another battery. Maybe I have to use an expensive speed controller. I don't know. But if your argument is that this highly efficient specialized DC generator can produce no more than 100 watts and barely over 2 amps no matter how hard or fast I pedal, I find it a little hard to find your criticism constructive.
Reality sucks.

So anybody with some advice on how to make this work with actual wattage numbers, please help.
Yes, please do. Help us both see the truth.

I just want to figure out a generator only mode for the batteries. Then a generator only mode to the motor. Then some kind of combined mode were the generator just adds a little more power straight to the motor.
I think I did a pretty good job at explaining that to you.

If this impossible, even with the Coleman Air diverter, then I shall retire from this thread with an apology for wasting your time.
I think I showed that it was not impossible, but worth about $0.01 per hour of your labor. It is up to you to decide if that is what you want to spend your time doing.

Regards,

major
 
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