Robert Forstemann struggles to toast bread via bicycle: AC resistance from the DVD player, 1.6 times higher than DC resistance

Tour Pros climb 15% slopes at speeds of 20 kmh outputing 400+ watts.

  Sure we can wind up a radio or keep those mini-screens on those gym bikes going but we quickly hit our limit when the energy demands get higher—anything involving heating for example.

By means of demonstrating this inconvenient truth, Robert Förstemann took on the challenge of heating a single slice of toast in a 700 Watt toaster with the incredible strength of his 74cm diameter thighs. Setting out at a steady 50km/h Förstemann battles with maintaining pace to keep the toaster going—the power required equivalent to climbing a 40 degree incline.

 I just don't know how they hooked up a generator to a monarch. Also there would be windage, bearing friction and AC/DC Inversion, at the very best he would need 15% more at source (cranks say 850 watts) Than load (toaster at 700 watts) 

https://www.lowtechmagazine.com/2011/05/bike-powered-electricity-generators.html

It is estimated about 50% of watts are lost due to resistance, converting, etc.
https://www.appropedia.org/CCAT_pedal_powered_energy_generator

The question here is this DC or AC power because if you're pedaling a bicycle, then the resistance is key. https://www.skoolie.net/forums/f49/dc-watts-vs-ac-watts-28596.html

 12vdc@6amp=72w or
120vac@0.6amp=72w

So same watts but dramatically different resistance!

The current I in amps (A) is equal to the voltage V in volts (V) divided by the resistance R in ohms (Ω)

6=12/x or 6x=12 so Ohms=2
.6=120/x or .6x=120 so X=120/.6  so 200 Ohms.
That's a HUGE resistance difference.

So maybe it was DC generator so then  .206 ohms since 700 watts/12 volts = 58 amps and ohms= 12/58

 For example, a 100 watt light bulb operating on 120 volts AC will have 144 ohms of resistance and will draw 0.833 Amps.

 

One thing not mentioned here. It is quite easy to safely wire AC from one end of your bus to the other to run any 120V appliance. Twelve gauge will run pretty much anything rated for 120V at that distance.
With DC you have to run increasingly larger wire as power requirements and distance increase. And the size requirements go up quite rapidly.
My fridge, microwave and induction cook tops are about 20 feet from the power source. Wouldn't have been feasible on DC.

A lower voltage system will require a higher amount of amps to deliver the same amount of power.

As an example, a 1000w load, will pull roughly:
83.3A @ 12v DC (common DC voltage)
41.7A @ 24v DC (common DC voltage)
20.8A @ 48v DC (common DC voltage)
8.33A @ 120v AC (US AC voltage)
4.54A @ 220v AC (EU AC voltage)
1.00A @ 1000V DC (common max string voltage for solar)

Your wire size is proportional to the amperage it will carry, and the round trip length of the wire run. For a given load, higher voltage = lower amperage = smaller gauge wire. I don't believe it makes any difference whether its an AC or DC circuit.

 yet:
 https://www.quora.com/Which-one-is-more-AC-resistance-or-DC-resistance

Due to skin effect AC exhibits more resistance than DC.

To reduce the resistance on AC wires with more thickness and high guage are used. The same resistance will cause a fuse to trip in cases of short circuit as fuse's conductive sting is thinner.

The puzzling part for begineers might be if AC already has high resistance then why high ohm resistors are used in series with AC ? . This is because due to skin effect and the conductors used to carry it to your equipment the amount of decrease in voltage with respect to resistance is never known exactly. So they will have to maintain an isolated voltage for their circuit Irrespective of external factors. The resistors helps maintaining isolated voltage.

 The tendency of an alternating current to flow near the surface of the conductor is known as skin effect. As the frequency of the current increases, the current tends to concentrate around the outer surface of the conductor. The current density is largest at the outer surface of the conductor. Thus, the effective area of the conductor decreases when alternating current flows in the conductor, therefore, the resistance gets increased.

 https://www.quora.com/Is-12-Volts-of-DC-the-same-power-as-120-Volts-of-AC

 But here is the reason that 120 V can deliver more power: wire size. Higher voltage requires thicker or better insulation, but higher amperage requires a thicker conductor. Amps is the measurement of how many electrons are travelling through a wire, so as it gets larger so does the wire.

So....

 converting slopes into ohms?

https://bicycles.stackexchange.com/questions/7774/how-do-i-calculate-the-power-required-to-climb-a-hill-at-a-given-cadence

This is the crucial question - whether it is AC or DC it's both a lot of Ohms. So Resistance as OHms is voltage squared divided by watts. We know the watts. If it is 120 volts then it's 14400/750= 19 ohms. The Toaster is 120 volts - so the bicycle generator is probably 120 volts. I have charged up at 3 ohm or 4 ohms - and I could barely pedal!!

 Actually the "pedal power" products are very misleading because they don't include the resistance. So you have to get up to a certain amount of volts to power 12 volts - and/or 120 volts. So if the RPM is alot then it can also change the resistance. So his resistance is very high - probably 19 ohms. You probably could not even turn the pedal at all. For example a 12 volt 60 watt light bulb has 5 ohms and it's very difficult to maintain pedaling at that resistance.

So Pedal-A-Watt is only producing 1 to 2 amps - at 12 volts - vid

78 bicyclists at full power cycling to power one hot electric powered shower  - BBC vid

Bicycle generator charging at 4.5 amps current 12.6 volt DC-DC buck conv...

Going into the Ecological Emptiness: Roger Penrose and Paul Beckwith and Bergson

Paul - you're being racist with your geographic immunity claim. The diseases that Westerners spread were diseases from intensive farming - intensive monocultural farming not practiced in the non-western cultures. A good book on this is called "Ecological Imperialism" by professor Alfred Crosby. Recent DNA science, for example, proves that Western white skin is from lack of vitamin D in the monocultural wheat farming diet. This can be traced even as Westerners, the Vedic brahmin culture, invaded India using chariots.

Paul Beckwith on Global Warming and Corona Virus 

Why was Entropy so low at the Big Bang? It is not "fine tuned" for life.

 https://consciousnessofsheep.co.uk/2020/03/01/our-second-greatest-shortcoming/
Inverse Exponential Energy Use chart in comparison to exponential growth of Western civilization across the planet - and exponential growth of intensive agriculture diseases

Thanks to long term correspondent - Guto - for this vid on Sir Roger Penrose cosmology 

Congotronics playlist 

And so we dance as Taiji healing energy - "moving of yin and yang."

 Dr. Stephen E. Robbins new Bergson video 

Sir Roger Penrose inspired physics response to Bergson

 and

DC Treadmill motor Bicycle generator DC-DC Buck converter for 4 amps cha...

So the internal impedance secret of the Chafon generator appears to be that with the charge controller turned on - it is an AC controller so has a low impedance resistance for input values. So that is why the battery did not draw in the motor energy. So then it must switch to DC internally and when it is turned off then the DC impedance for 31 amphours kicks on. So it's the internal impedance of the battery that then makes it difficult to PUSH in the energy - as the resistance goes up from lack of battery draw. So the AC charge controller must limit the amp draw that can be pushed in. So then when I increased the DC-DC buck controller to 14 volts output - then the draw of the Chafon pulls the volts down less. The volt input into the Chafon has to be above 12.2 for the amp load draw to kick in but it's not until the treadmill motor RPMs are high enough in volts does then the amp draw get high enough to overcome the pull down in volts from the battery load.

DC-DC Buck Converter now achieving 4 amps charging current into 31 amphour Chafon 346 watthour generator

I finally did it! I will upload the video first.

4 amp charging current from treadmill DC motor bicycle to 12 volt lithiu...

The Internal Impedance Secret: How lack of Ohm discussion has been used to sell the bicycle generator as a noted scam alert

In the above example the alternator can cut in at a very low rpm and produce 12 volts for battery charging, but its internal impedance is evidently very high which means that the output current is pitiful.  Current in amps to charge a 12 volt battery will be lower if anything than the tiny short circuit currents quoted in the above list.

Internal Impedence - meaning Ohms as the "back emf" force.

 Since there is no load, these are called the open circuit voltage and short circuit current..............

The seller responds:

 I then, over the course of many emails, supplied full details of my system (and relevant details of my neighbours’) with photographs of all wiring plus regular updates on the rpm of the units and the power they were generating, making clear on every occasion that this was being measured open circuit with no load, which is the same conditions under which they produce their power curves. And we weren’t using a tachometer. We were counting wheel revolutions over a timed minute and multiplying that by the gear ratio, so we knew the rpm of the M-24s (+/-5% depending on whether you calculated the ratio by gear wheel diameter or number of teeth).

http://www.permaculturinginportugal.net/never-count-your-chickens-before-they-are-hatched-or-your-alternators-before-theyre-run-in/

So they are still selling a claim of 400 watts being produced.

 If your goal is simply to inform readers that they need to be aware of loaded power output, “rated” power output for battery bank environment i.e 12, 24, 48 volts and or resistance as programed by a direct grid tie as the load at a particular cut in. I tip my hat good luck and I spend a lot of time personally educating our customers in kind.

But if you read the above comment - from this blog analysis - also cited above - there is this serious caveat that I don't see mentioned on their website:

Meantime the practice of quoting short circuit current and open voltage are the actions of people who are motivated by profit ahead of helping their customers and I will not shrink from saying so.
I suppose you guys do know how to measure power output? Measure the DC voltage and multiply that by the actual DC current into the battery at the same time. Go ahead and do that with honesty and I shall make an announcement on this blog about that.

And so a customer sent in a fraud complaint:

 The crank a watt generator sells as a 1600 watt unit that in a video Tim Meoller who claims to be an engineer states his product will run a microwave and nothing could be further from the truth. This is a glorified car alternator in a cheap plastic case made with simple cheap electronics and inverters that you could find at harbor freight. One would think for 2000 $ you would be getting a premium product but I can assure you this is not the case. My opinion is that the people believe  that this thing will be put away until the moment of truth. luckilly we test everything and will not depend on this wiley cyote contraption for a thing. People save your money this one is a lemon. Me bough the “400” watt model. If we had bought the $2000 two man job it would be even worse. Do not plan to give this thing a few cranks and do what the guy does in the videos…its not happening.

 https://www.ripoffreport.com/reports/prestowind/cincinati-ohio-45245/prestowind-crank-a-watt-crank-a-watt-tm-rip-off-cincinati-ohio-992427

So it is quite amazing - that I did not get any responses when I posted two questions on Ohm resistance - to supposed "experts" - and so I went ahead to test this on my own - via the 60 watt light bulb at almost 5 amps output. So in other words - I can get 5 amps but only because there is a higher ohm resistance that MATCHES the internal impedance of the DC motor generator! And because of that higher resistance then there's no way to maintain that pedaling power for long. It's just an experiment to show that the DC motor can create the level of power if needed.

So from the youtube comments on one of the vids promoting this generator.

beware buyers a heads up when you do not receive your product and you call to find out what happened they will also tell you they return your money and they do not know where it is now beware

and this:

attention attention all buyers Tim Moeller at Moeller engineering is taking people's money and not sending them the product he will tell you he don't know where your money went but he does not have it he is currently being investigated through PayPal for fraud do not buy crank a watt

 20 watt limit on the 120 volt DC generator...

 167 milliamps

Yeah and then you have to convert it... to a 12 volt battery!!

windzilla 24VAC Max 2000W Permanent Magnet Alternator Wind Turbine Generator PMA

So this is probably the same machine?

With the Speed-Up GearBox, this alternator will reach 24V at as low as 50RPM

China selling another "set up" - it's half an amp charge. So 12 volts - putting out 6 watts.

https://www.thegreenmicrogym.com/the-story-of-the-upcycle-eco-charger/

An athlete can average over 100 watts and peak at over 500 watts.

Yeah but the RESISTANCE on 100 watts is gonna be huge!!

Keep in mind the key here is AMPS. So when I charged up the 60 watt light bulb that was at 5 amps!!

I can do 120 watts at 60 volts or 50 volts - so it is 100 watts but I am using the DC-DC buck converter to get 2 amps - so that the resistance is much less going into the battery load.

https://www.scienceshareware.com/bicycle-generator-faq.htm

Why are the amps so low?

3 Volts was put on this armature which drew about 4 amps.

So the resistance is negative? It's kicking out a huge amount of heat - strange.

 OH so he has to STEP UP the volts to get to the higher amps at lower RPMs. So the ohm resistance is lower but you have to pedal much faster. So he gets 10 amps but at lower volts than 12 volts. So how much is lost by stepping it up? You LOSE amps to step it up.

So at 10 amps you lose have the amps to convert it to 12 volts - from 6 volts. So you get 5 amps at 1500 rpm. But does  he use a DC boost inverter? Doesn't look like it! He just uses an AC inverter....after first charging to 12 volts?

So to get to 12 volts you have to pedal super fast?

When there is a big surge in current, you may see a dip in the voltage being supplied by the voltage source.

So the charge controller is AVERAGING out the high current as being TOO low in volts!! and that's why the overall amps are so low...

Fascinating. I wonder if using this 12volt DC motor with a DC-DC buck converter will then enable an even high amps at low ohms?

OH I forgot - the low ohms also creates too much heat for such a small motor. It's only rated to 40 watts?

Keep in mind that most motor armatures can run at a temperature as high as 100 Degrees Celsius.  But be warned that if you operate at that temperature or higher, you will start to smell a strange burning electrical smell in the room like when a blender gets too hot. 

In this experiment above only 3 Volts was put on this armature which drew about 4 amps.  Using the formula for power: Volts X Amps = Watts we can say that the armature was dissipating 12 Watts of power. After 10 minutes it rose to a temperature shown at Marker 1 above of 73.3 degrees C.

So he's saying there's actually a below 4 amp limit anyway?

 Although I don't have anything against pedal powered electricity, practical experience has shown that it's not very useful. I certainly don't want to pedal for 2 hours just to charge my cell phone battery, either!

So the "Pedal Power" dude states 10 years ago:

Most Treadmill motors are rated to handle a max current of 6 or 7 amps which would only let you deliver around 100 Watts of power. The leeson M1120046 is rated for 14 Amps which translates to about 200 Watts of delivered power when charging a powerpack or lead acid battery at 14.8 Volts ( 14 Amps X 14.8 Volts = ~ 200 Watts.

Yes but the Impedance DRAW of the battery is much lower - compared to the impedance of the treadmill motor! Oops.

OK here is a DIYer - also using a 12 volt DC motor - and not SELLING anything.

So he posts a video with his amp load - and yep - in highest bicycle gear he is also just getting 2 amp output.

So his resistance is low but the amps are low also.

https://ecorenovator.org/forum/showthread.php?s=50667d494d85c29e7d664026563ac27b&t=325&page=2

15 pages of forum on his set-up!

So that lower amp though it all depends on the load draw... he blew out a 6 volt bulb since he pedaled to slow - and the load draw on the bulb had a much higher impedance! So how will the load draw be on his 12 volt battery that he just bought...

 65 pedal RPM, and ~7000 motor/generator RPM; to get the highest power output, I had to spin fast enough to be impractical (also the voltage is too high to feed a battery for a long time - I'd cook it.)

The biggest problem with using a 12v permanent magnet motor is the RPM it needs to spin to generate useful (> 12.6) voltage. The calculations: I need to spin the pedals at least 65 RPM to see the battery voltage start rising at a reasonable rate. 65 pedal RPM = 248 wheel RPM in top gear = an astounding 7090 RPM for the motor/generator (7/8 inch hub diameter).

 yep so that brings us back down to about 2 amps for a safe charge on the battery.

So the PedalPower person is making this claim for a bicycle using his DC generator:

75 to 400 Watts

6.2 to 33 Amps @ 12V

 I just don't see how this is possible.

Because he's not saying that the volts are actually BELOW 12 volts - that is before the conversion.

So to get up to 12 volts then he is losing the amps and the amps go down to 2 amps. Oops.

But the battery in the circuit battery adds a fair amount of resistance to create X watts of output from the inverter, because I'm also charging the battery (or at least trying to maintain its current state of charge).

So as I said before - if you use an AC inverter to increase the DRAW on the battery - then the internal impedance on the motor goes way up - because the load is just like a light bulb load.

A permanent magnet alternator (not most automotive alternators) is ideal.  ...For example, my first implementation (try to hold input voltage at about 16V or so, but decrease the limit down to 10V in order to hold a 3A minimum current) worked great when I tested it, but oscillated wildly when my friend Sarah tested it.

So now you're cycling in highest gear but the DRAW load is the real resistance - not the motor load.

Fascinating. So it's the exact opposite as a high voltage DC motor like I have - whereby I have a higher draw load at lower RPM.

 The small dia wheel I needed to use to get enough voltage from my 12v motor generated too much heat and friction and started wearing out the tire sidewall.

 

http://www.los-gatos.ca.us/davidbu/pedgen.html

 the permanent magnet 36 volt DC motor...For electricity storage I would charge a 12v 100Ah fork-lift battery. I could approximate the output of a small 10 amp battery charger.

So - here's another set up. Wow that person has the MOST EFFICIENT set up so far!!

 So he get 5 amps power with very little resistance effort. - video - that's a big tv

Here's the 5 amps powering the 12 volt tv - AMAZING!!  - very little resistance and rpms

My Pedal Power History: 35 Years Researching the Power of Human Energy

https://www.electricpedals.com/

a fourth set-up!!

So this person uses an inverter directly - vid - but says there's the 10% limit to the amp hours of his battery - so he can't go over 2.5 amps for long

hmmm....

fascinating. So smaller battery and inverter - but still have an amp limit!

https://www.popularmechanics.com/technology/gadgets/how-to/a10245/pedal-power-how-to-build-a-bike-generator-16627209/

What about "Pedal-A-Watt"? I am waiting for their response:

what is the volts needed to make 100 watts - because your rpms create the number of volts. So is there a converter to increase the watts by Buck converter?

ConvTech

7 hours ago

Thank you for your question. WITHOUT the voltage regulator the voltage varies and may be as high as 90 volts DC depending on how fast the rider pedals. Using the 12 vdc regulator option, the output is a steady 14.2 volts DC which is needed for 12 volt appliances and battery charging

 Thank you for your interest in the Pedal-A-Watt. The largest factor in how difficult it is to pedal is the load, i.e. what it is you are trying to power or charge and how much energy it requires. A small load is like riding a bicycle on flat ground and is very easy. A large load is like climbing a big hill and is more difficult. This is why we recommend using a bicycle with multiple gears. It is much like when you are out riding a bicycle - with multiple gears, you may change gears when climbing a hill or moving on flat ground to make pedaling more comfortable. The resistance changes as the battery becomes more charged and as the generator RPM speed varies so it is not a constant figure. For those interested, it may be calculated using Ohm's Law: ( R ) [ R = V ÷ I ] R (Ω) = V (volts) ÷ I (amps). Our Power Meter option allows you to view Watts, amperes and volts in real time and may be seen at www.econvergence.net/Power-Meter-for-the-Pedal-A-Watt-p/pawpm-1.htm

 ConvTech OK so you're saying that it's hard to pedal if there is greater resistance in the battery based on it being more charged up. And so then - what is not clear is that pedaling at higher gear RPM will increase your volts but it won't enable you to pedal with greater force. "you may change gears when climbing a hill " So the load from the battery draw is greater when the battery is more charged up since its resistance then increases? Or is it the opposite because the battery will pull or suck in more power when it is not as charged up - and therefore the generator resistance going out will be less? And most importantly - if you are pedaling at 90 volts - does your 12 vdc regulator then step down those volts to then increase the amps going into the battery? Or are you saying the pedaling volt level (say 60 volts) will change so that when the battery resistance is low due to it needing more charging then it's load draw will be less - so you can pedal with higher bicycle volts and the battery will draw those volts down closer to 14 volts? thanks

ConvTech

Voidisyinyang Voidisyinyang Thank you for your interest in the Pedal-A-Watt. A battery that is fully charged offers very little resistance as it is not drawing many amperes from the Pedal-A-Watt and it is easy to pedal. A battery that is totally discharged will pull more amperes as it charges from the Pedal-A-Watt and will be harder to pedal. Yes, the 12 vdc regulator/converter ensures that the output voltage is 14.1 volts DC and in your example decreases the input voltage from 90 volts DC and increases the amperage to keep total output wattage the same as the input wattage (Remember, Watts = amperes x volts).

Great to hear! Thanks for your concise, straight forward explanation. So that explains to me that the battery energy draw is based on volt level because for example if I use a multimeter on volts then it is very easy to pedal as there is very little draw from the multimeter. But when I switch to amps then there is great resistance from the multimeter - because it also has no load for the amps as well. So as you explain when the battery is loaded up with amps it is easier to pedal because it is the volts causing the draw, not the amp level.