HP for Alternators

[TheKid]

Back in the 70's, I toyed with the idea of using human power to spin an alternator to either recharge batteries, or directly power an electric motor and lighting system. It was too expensive for me at the time, so I never gave it much thought until now. The idea is to use a normal bike chain system similar to the DW, DR, etc., but the rear axle would turn a 20" flywheel/pulley instead of a wheel, which would in turn, spin the alternator pulley. The momentum of the flywheel would allow intermittent pedaling, just like a bicycle. I figured that since there wouldn't be much resistance, a 53 tooth chainwheel with a 16 tooth freewheel would do the trick. If there's a way to get an alternator to produce more than 13 volts, or to hook the flywheel up to 3 or more alternators, it might work.

[greenevegiebeast]

Kid I have seen some Bike alt conversions where they used a normal wedgie bike atach to a modified trainer with an alternator atached via belt drive.
If I were to atemt it (not in my curent plans to many projects right now) I would use a Up Amped GM style onewire altenator. that woul simplify the wiring and build.
I think I say that build on Instructibles.com

[AtomicZombie]

Using a car alternator is about the worst possible way to get human power. The massive losses and huge RPM needed are real issues.

You could rip the alternator apart and replace the stator fingers with NIB magnets to get a decent amount of power, but this would still be a lot more work than using a better motor/generator.

A treadmill motor, powerchair gearmotor, cycle hubmotor, or just about any PM DC motor will do the trick. Almost none of the links that have working units use a car alternator...

http://images.google.ca/images?hl=en&q=pedal%20generator&um=1&ie=UTF-8&sa=N&tab=wi

If this is a project you plan to get a lot of use from, maybe a brushless 400 watt rear hubmotor would be a good choice? Ready to run, low RPM, huge efficiency.

Brad

[greenevegiebeast]

Brad the rpm thing can be overcome with gearing, the bigist problem I see is the fact that most normal auto alternators need a field curent. by using a one wire type gm style alt, you bypas this issue. then there is the fact that they have a built in regulator.

as the gearing goes the alt I am thinkimg about needs to spin @ about 9000 rpm+/- to start charging. with a 2inch pully versis a 26 inch bike wheel this should be easly acomplashed. as for efencey, no they are not efecent.To get beter efencey you would need to use a more modern style alt, they are more efencent. though the comlplication goes up as well.

[TheKid]

I have some old alternators that put out 13v @ 3600 rpm. Those were the ones I was going to use over 30 years ago. By now, they may have deteriorated to the point of being useless. I haven't tested them since the '73-'74 gas shortage. The hub motor seems like a good idea. How many volts would it generate? This is not an area of expertise, but my logic is to generate enough to power, or charge the batteries for, a 36v motor, and power a 12v lighting system, or a battery for the lights. Another question, can hub motors produce a constant voltage at variable speeds? I'd still want to implement the flywheel so constant pedaling would be eliminated.

[AtomicZombie]

The needed RPM + the ultra low efficiency is exactly the problem. Compared to a decent treadmill motor, you will be doing most of your work to fight friction through the jackshaft.

As a science fair demo, it would be cool to spin like mad and light up a small bulb or portable TV for a few seconds, but other than that, car alternators do not have much use out of the car.

Brad

[macka]

How much electricity can a power chair gearmotor make? I know where a busload of them are here, and if its better then an alternator then its bonus for me as they are free if I ask. All I know about the chair motors is they are from the mid 90's and have an E&J chair with a power unit.

[AtomicZombie]

I wish I would have run more tests on this 24 volt powerchair gearmotor I had connected...

http://www.lucidscience.com/temp/gendrive.jpg

I was able to get my grinder, drill, and some large lights running with moderate pedal effort. The plan here was to charge a supercapacitor buffer (not the beasts in the photo) in order to put human power into the hybrid.

I can tell you that there is no comparison at all to a car alternator - this system kills it without question. Yes, I tried the car alternator once as well.

So far the best low RPM generator I have found is my 400 watt brushless hubmotor. The next best one was the small wind generator from the department store.

Brad

[TheKid]

So the hub motor can generate enough to run another hub motor and a 12v lighting system?

[greenevegiebeast]

onlyin dream land could one hub motor run another hub motor of the same size plus the lighting system. the only way I see that that would work is with a perpitual motion machine.

[AtomicZombie]

Yes, one hub motor can run another with a certain loss. I actually had the rear of that massive trike connected to another DC motor and was able to pedal around using only the generator. You could feel the losses, but it was less than I thought.

The hubmotor is such a good generator that if I place the AC cord from my angle grinder on the output, the grinder disc will spin with a simple flick of the hubmotor wheel. I just did this today while I was working on the CycleBully trailer.

Brad

[macka]

Yes but if you are looking to increase the range on an e vehicle, this would be a nifty setup. Thats what I was eluding to on my other post. I should have mentioned that.:o

[John Lewis]

Pedal generators were common here many years ago. When Rev John Flynn started the Roal Flying Doctor Service He had Alfred Traeger design the radio system (Morse code back then at first ) . In order to power the radio Alfred designed a pedal generator. This was used on the outback stations (ranches) for many years.

The outback children had School of thr Air. Imagine pedalling madly so you could communicate wit your teacher!

I have only seen one in a museum so can't comment on how efficient they were. Perhaps savarin has some information if he reads this. I think it all started up in his neck of the woods.

John Lewis

[AtomicZombie]

But it would only reduce the range on a e-vehicle due to drag.

Here is another analogy...

I want to weigh 155 pounds this week, but am still hitting 160. I know, fat is now muscle from the weight training, but that's not the point. So what I am going to do is get on the scale and then grab hold of my belt and lift myself up so that I am lighter.

Nope, won't work either.

How about this one...

Want to extend the life of your flashligh batteries? Put a solar cell in front of the beam and feed it back into the batteries. Seems logical?

Nope, just blocks the light, now you have to use more power.

There is simply no way to regain the energy output of an electric motor and feed it back into the system for gain.

If you claim that you did this, then you would be heading to the rubber room with these dudes...

http://www.steorn.com/orbo/claim/

or even worse....

http://www.world-famous.com/DavidHamelStuff/Hamel-Part3-Blue/index.htm

This dude is going to get abducted again! Yikes.

Ok, now I am going over the deep end to make my point.

Brad







Yes but if you are looking to increase the range on an e vehicle, this would be a nifty setup. Thats what I was eluding to on my other post. I should have mentioned that.:o

[TheKid]

I believe it's already proven that you can extend the range of an e-vehicle by using a HP generator when the batteries have been exhausted. That's how I got the idea in the first place. I didn't know you could use a motor as a generator, hence the idea of using alternators. At the time, I also discovered that it would take a long time to recharge the batteries, so going to HP generation to power the motor AND recharge the batteries at the same time doesn't work. (Also proven on Mythbusters years later.) So, if you could get 20 miles out of a single charge, then switch to HP generation, your range would be extended by the length of time you could keep pedaling. That's where the flywheel comes in. It allows short periods of rest. I had the flywheel hooked up to an alternator back then, and hand cranked the flywheel via a bike chain system, which spun a 26" modified bike wheel with a freewheel on the right side, and a large pulley on the left. The wheel had a 3lb. hammer head duct taped to it, so it acted as a flywheel. The alternator put out voltage for 10-12 seconds when the pedals weren't being cranked.
The hub motor idea puts a new light on things. Lightweight batteries could allow two or possibly three sets to be used; when one set is spent the next set kicks in, allowing 30 or more miles before having to use HP generation, depending on the amp/hour ratings of the batteries. For a single person lightweight vehicle, I believe it would be possible.
I'm hoping I could still find the plans for a delta trike that's made of epoxy over foam. The base was a single length of foam, 23" wide x 9" thick.
I'm not looking for speed, 15 to 20 mph would be fine. So to improve efficiency, would using a 1000 watt motor for the generator and a 750 watt motor to drive the vehicle be better than two 400 watt motors?

[John Lewis]

When the power runs out it will be more efficient to pedal directly. If you use a generator to power a motor to drive the wheels then you are only adding inefficiency. There are losses associated with the generator and then further losses in the motor.

The chain drive from the pedals to the wheel is as far as I know the most efficient way to power a bicycle.

Of course you may have a compelling reason to drive a motor from a generator.

John Lewis

[macka]

So metaphorically speaking Brad, is there a way to "put a pulley and harness" on the ceilling so I can ull myself up, or am I looking at the pulley and harness being powered by an outside source like an engine powering hub motors etc.?

[AtomicZombie]

On your pulley system, the energy required to pull you up is transferred to the ceiling, where the block and tackle would attach. So metaphorically speaking, you still could not make yourself lighter by trying to lift yourself - all your weight will still be suspended by the bolt holding up the hardware. There are no gains, just a change in mechanical advantage through the block and tackle. You have traded speed for distance.

Dropping a generator on an already moving electric vehicle in an attempt to recover the power is futile, even at 100% efficiency, which is impossible. Even if 100% efficiency were possible, the energy required to generate 100 watts would be 100 watts. In a battery buffered system that would probably drop way down. After friction and motor/battery inefficiencies, you would probably be putting out 10,000 watts to recover 100 watts.

Try this...

Get a small wind-up car toy. Hack it so that the drive wheel also turns the windup crank through a gear reducer. I will bet you everything I own that you will make the unit so much less efficient that it barely makes it across a table now. Same deal with electric.

Now regen is something altogether different. You climb a huge hill, and then regain a tiny amount of energy on the way back down. There is nothing gained here though as the energy was already lost up the hill. On flat ground, this is completely useless.

Brad



So metaphorically speaking Brad, is there a way to "put a pulley and harness" on the ceiling so I can pull myself up, or am I looking at the pulley and harness being powered by an outside source like an engine powering hub motors etc.?

[TheKid]

There is simply no way to regain the energy output of an electric motor and feed it back into the system for gain.


Of course you may have a compelling reason to drive a motor from a generator.


When I worked for the county, I participated in an experiment replacing the gas engine on a generator with a 220v motor that drew 7.5 amps. The generator produced enough energy to run a fridge, some lights, a TV, (Shows how much the bosses actually worked) and a couple of power tools. There was a significant savings in electricity, according to the electricians.
So scaling it down from my previous question, If you use HP to spin a 750 watt hub motor, the person would replace the 220v motor in my experiment, and the 750 watt motor would replace the generator. Instead of powering a fridge, TV, fluorescent lights and power tools, it would power a 400 watt hub motor, and a lighting system using low power LED's. Assuming the lights would use a maximum of 20 watts, that's 420 watts. The energy loss from the 750 watt motor would have to be over 40% for failure. That seems like a high number. In other words, I'm not looking to regain the energy output, 70% would be sufficient. What I'm not sure of is AC vs. DC. Would the results of the experiment be duplicated in DC? Or are there more losses?
I could think of a few reasons for HP generation. It would eliminate the need for batteries and building storage for them. If you used it for extending the range of batteries, I'll use my DR as an example. It weighs about 60 lbs. now. Adding batteries would add another 15 lbs. or more. It's a lot easier on my tired legs to spin a hub motor while travelling uphill than a propelling a 75+lb. vehicle. Add to that that I'm envisioning a fully faired trike, so the weight is more like 100+ lbs. Any inefficiency in using such a system is far less than my tired old legs.Of course you may have a compelling reason to drive a motor from a generator. :D

[AtomicZombie]

Yes, I agree with Papa - we are bad engines for generators!

TheKid...

Now, I must concede, I just can't grasp what you are trying to say here. No matter how I read your explanation it sounds like a generator running a motor running a generator running a motor..... AKA - free energy.

No matter how I try to envision this, it's just a huge loss of power in the end.

Brad

[TheKid]

No free energy here. Just like the batteries, when the body runs out of energy, the vehicle stops. The chain is human-generator-motor-drive wheel, as opposed to battery-motor-drive wheel. My question is how many rpm are needed to produce the maximum wattage? I know for a fact that I can easily sustain 80 or 90 rpm with the drive wheel off the ground (Which is essentially the same as spinning the hub motor to produce electricity) far longer than I can with the wheel propelling the trike, with a 4:1 ratio. In physical therapy, I ride the stationary bike for 20-30 minutes at between 90 and 100 rpm with some resistance dialed in. (The therapist sets the resistance, I'll have to ask how much it is next time I go.) I could go longer if I have to.
IF, and I'm asking, not telling, 280 - 360 rpm is sufficient for a 750 watt motor to generate enough to power a 400 watt motor, then would it be possible to propel the trike until the body ran out of energy? If so, in essence, what is being done is a reduction of friction. There's less friction involved in spinning a hub in free air than there is with wheels to the road.

[John Lewis]

If you want even 150 watts out of that motor you will need to input considerably in excess of that to make up for losses. For arguments sake lets say you have to input 250 watts.

You will have just as much if not more resistance to overcome from the alternator. Think mag trainer screwd down hard and then some. The alternator resists your efforts. A mag trainer is in effect an alternator with a heavy load on the output. Get hold of a dc permanent magnetmotor or generator, even an old bike dynamo. Short the output and try to spin it by hand. You'll see what I mean.

Most certainly you will expend more energy running through the alternator motor route than you will if you remove the alternator and motor from the equation and just pedal.

John Lewis

[John Lewis]

Quote: "replacing the gas engine on a generator with a 220v motor that drew 7.5 amps."

That's 2.2 horsepower. Volts X amps = Watts and watts/750 = horsepower if I recall correctly.

John Lewis

[Trailblazzzzzer]

I read an article about a car that runs on compressed air.
I think they were building them in India. They weren't very efficient in that the generator ran on propane and weighed hundreds of pounds.
The tanks held 3300 psi of air pressure.
It made for a very slow and noisy vehicle.
I had an idea conjured up from my Juvenile Delinquent youth...
I used to explode mail boxes with a combination of various chemicals mixed in plastic 1 litre bottles.
Why couldnt we produce 3300 psi with this type reaction and channel it into Scuba tanksand power an air motor (1" air impact wrench)?
Most impact wrenches have 1000 - 1500 ft/lbs torque and 5400 rpm.
That should be enough to power my StreetFighter to about 95mph.
or until my wheels fall off, bustin off the regulator and sending my scuba bottle and self for a real land speed record.
No, I havent tried it yet. Im not an engineer. But if the AZ Krew temps me....
... i will send pictures from the hospital...
Davo

[AtomicZombie]

Ok, now I am seeing what you are talking about - using a wire as your transmission.

Yes, this is exactly the tests I did on the trike photo I posted. It felt like a slugish clutch system of sorts. I had to pedal at about 60-100 rpm on the generator to get the unit to move while the motor and generator were wired directly together.

With one 400 watt hubmotor running another, you would probably see a loss of about 50%, so it would be as if you were pedalling with one leg.

Does it work? Certainly it does, but only as a novelty or fun experiment. I actually intended to use the gendrive on my 30 foot tallbike since managing such a long chain would be difficult. The gendrive would also serve as a smooth brake by simply resisting the pedals as they were forced into motion by the rear motor (now acting as a generator).

As for motor power, you would never need a generator or a drive motor over 400 watts if your plan was all human input. Those wheelchair motors were rated at 250 watts, and I could not heat them up no matter how hard I cranked.

Brad

[TheKid]

I called the electrician who led the experiment at work. The first thing he asked about was the voltage for the 400 watt motor. I said 36. After a few moments, he answered that to produce 36 volts, the generator has to be spinning at 2700 rpm. As far as wattage is concerned, it doesn't matter if it's calculated from electrical energy, or translated from physical energy to electrical energy, resistance is one annoying variable that can change at any time, reducing or improving efficiency in a matter of seconds. He cited a perfect example, encountering a hill while riding a bike.

[AtomicZombie]

He is way off base with the voltage part. Even at 200 RPM, the hubmotor will spew our more than 36 volts.

I fried a 12 volt bicycle headlight when testing the hubmotor as a generator by simply turning it with my hand.

If you like, I will post a video of the grinder spinning as I spin the hubmotor by hand. I know for a fact the grinder will not start up on any less than 30 or 40 volts.

Brad

[TheKid]

His whole answer was rather lengthy and technical, but it came down to in order to get the 36v and adequate amperage with somewhat acceptable, but not nearly optimal efficiency, I'd have to be spinning the generator 2700 rpm. He asked about physical and electrical resistance, which is info I don't have, but is important in order to give a definitive answer. He basically said the possibility for it to work exists, but it's a long shot.

[AtomicZombie]

Well, I can't offer you a bunch of complex calculations and math, only my real world experience using the hubmotor as a low RPM generator.

If you would like me to test it using some other type of load, say the word - the hubmotor is still just sitting there in my trailer frame.

Brad

[macka]

how about seeing it power a compressor?

[TheKid]

Thanks Brad. I'll have to get more info on this. I've heard of people using this method as an exercise machine that powers a TV and lights while they're exercising, and one guy uses it to power his computer so he could surf the Net while exercising, but I guess these appliances don't draw much power.

how about seeing it power a compressor?

Now there's an idea.

[AtomicZombie]

I don't own a compressor, but I have tried it on the grinder, hand drill, several car lights, and directy into many 200-500 watt DC motors.

The rear hubmotor would be ideal as it includes all you need to just add a crankset. When I was testing my hubmotor, I just spun it up either by hand or by letting the chuck of my drill rub on the 20 inch tire.

Brad

[macka]

does it get the 500 DC motor spinning good?

[AtomicZombie]

When testing the spin of the hubmotor and drive motor, there seems to be almost no loss. It wasn't until I tried pedalling a generator into a drive motor that I felt how much loss there was.

I still say there is no better low RPM human pedal generator better than a small hubmotor.

Look at how well one hubmotor runs the other - seems like magic...

http://www.youtube.com/watch?v=UXi2yn7RRSc

Because the have strong NIB magnets rather than coils, they are so much better for low rpm and efficiency when compared to a clunky car alternator...

http://cr4.globalspec.com/PostImages/200710/High_Speed_SRM_Hub_Motor_Exploded_View_9744FABA-F431-409A-1B97575137EBF678.jpg

Brad

[Sparky]

i have heard about an all plastic, 2 seater, pedal powered car. of course, its electric. sold somewhere in europe for stupid amounts of money.

as it was explained to me, it ran off batteries. however, humans pedaling generators inside did a bit of battery recharging, which powered the vehicle further than the batteries could have sustained by themselves.

the advantage over a chain drive is this- you can pedal at a constant rate, and constant power, regardless of accelerating, deccelerating, or hills. and, you dont have to pedal, if you dont want the extra distance it would net you.

is that a reasonable thing to build? could your pedalling generate enough to make it worthwhile? like, if battery run time was 1 hour, but 1 hour of pedalling only got you 5 minuites more run time, thats not worth it. but it would be for 30 or 40 minuites more run time.

and is that what yall are talking about? im not really sure; all the wattages and hubmotor speak confused me. :)

[greenevegiebeast]

Sparky it is called the twike, it is nolonger being produced. From what I have found it was a bit of a joke as electrics, or hybreds go. I have seen sem pics and vid on Youtube some time ago.
I was going to find the twike on the ev pic forum, but it is down.

[greenevegiebeast]

http://www.evalbum.com/type/TWIK

[Whothe-whatthe?]

... From what I gather, a hub motor could also be used as an effective low rpm wind turbine generator. Maybe not enough to power a household, but certainly enough to charge an EVs battery pack, wouldn't you say?

I have a small river that flows slow and steady at the end of my property. I've been playing with a waterwheel design for a micro hydro generator to tap into the river's energy with minimal impact. A hub motor just might be the best candidate for that application.

[AtomicZombie]

The pedal generator system into batteries is exactly what my huge trike experiment was about. I also plan to use that system in my camper bike when I get back to it.

As for the Twike, maybe you are thinking about another electric trike?

The Twike is doing remarkable well now, and is now available world wide. An EV friend in Ottawa imported one a few years ago.

http://www.twike.ca/ (http://www.twike.ca/)

http://www.twike.com/ (http://www.twike.com/)

http://www.twikeklub.ch/ (http://www.twikeklub.ch/)

This is probably the most successful and most popular human/eletric hybrid in history.

Brad

[TheKid]

The pedal generator system for charging batteries was exactly what I had in mind originally. At that time, the cost of building such a vehicle was out of reach for me, and I was planning on using alternators, which of course, we now know would not work well, if at all.
The idea was to use marine batteries, because I was told even then, that car batteries were a poor choice for this type of project. If I were to attempt this now, I'd opt for lighter weight NiMh batteries, or lithium if the prices start to come down. I've been told that one of the great advantages of lithium is they take up less room.
At that time, I was told that it wouldn't work, because the idea involved perpetual motion. That didn't hold water in IMO, because once you stop charging the batteries, and the batteries run down, the vehicle fails to move on it's own power. What did make more sense, was when I was told that I'd need at least two sets of batteries, because you can't charge batteries as fast as they're being drained, but with 2 sets of batteries, one would be charging while the other was in use.

[AtomicZombie]

Everything you said there makes sence. You could get away with 1 batter, and this may be even better as the human input would go directly into the dive motor if needed rather than to charging. The most efficient way of doing this setup is still with a chain directly from the cranks to the rear wheel, but then you loose to cool factor of a "transmission via wire".

Brad