..... Would that be like the brexit thread debate?That would be very dangerous Zlatan. After powering the motor, the surplus of current from the dynamo would have nowhere to go and would heat up the system and destroy it. It's possibly why we haven't achieved perpetual motion yet, the self-destructiveness of closed loop generating and use systems.
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For those who believe in Miracles a Self Charging Ebike
- Thread starter oldgroaner
- Start date
Tommie , this is an argument you cannot win. Opinions no matter how strongly felt or expressed cannot withstand facts. Please go back and read my previous postings on this topic.
The only scenario where regenerative braking and power harvesting would make any sense is there a person was going down a mountain in the outward run and going back up it on the return. The braking effect of the power generation would reduce the amount of energy turned into heat by the brakes.
Dan, I think you`re missing my point here...
Many years ago i used to have a bike that had that SA type front hub, i rode it night and day, and i can assure you it made no difference to effort/input on whether i switched my little front light on or off, certainly not to the extent of a whopping 6%. It was a puny little bulb not the floodlights at Old Trafford on the handlebars!
Now trying to ignore our resident `merchant bankers` in here my serious question was to the effect - would that current from the hub dynamo (or the better dynamos of today), which was turning anyway as i pedaled, be of any use if routed into our ebike batteries over the course of say 100 miles?
Being able to spin this hub up freely by hand gave me the impression there was energy going to waste when i was riding normally and not using the lights
Many years ago i used to have a bike that had that SA type front hub, i rode it night and day, and i can assure you it made no difference to effort/input on whether i switched my little front light on or off, certainly not to the extent of a whopping 6%. It was a puny little bulb not the floodlights at Old Trafford on the handlebars!
Now trying to ignore our resident `merchant bankers` in here my serious question was to the effect - would that current from the hub dynamo (or the better dynamos of today), which was turning anyway as i pedaled, be of any use if routed into our ebike batteries over the course of say 100 miles?
Being able to spin this hub up freely by hand gave me the impression there was energy going to waste when i was riding normally and not using the lights
no because 1 the voltage is to low and 2 not enough constant current / amps.
even if you up the motor to 12v you then have to maintain that speed for 100 miles with all that extra waight going 20mph.
there is no way you can put in what you take out off the batt in the first place unless you have a 100 mile down hill run.
if a f1 car cant do it going 200mph+ then you have no chance as both will run out of fuel in the end 1 way or the other, knackered or ran of petrol lol
even if you up the motor to 12v you then have to maintain that speed for 100 miles with all that extra waight going 20mph.
there is no way you can put in what you take out off the batt in the first place unless you have a 100 mile down hill run.
if a f1 car cant do it going 200mph+ then you have no chance as both will run out of fuel in the end 1 way or the other, knackered or ran of petrol lol
yeah, know what you mean SW, but i`m not after perpetual motion, only the possibility of adding a little time, say 15mins to the battery life over 100 miles or so
you could charge a 5v batt with it but not the one on the bike as would need a 12v motor to power a charger and then the extra waight is just not worth it.
http://uk.gpbatteries.com/uk_en/powerbank/f-series/fn03-1?gclid=Cj0KEQjwn_3GBRDc8rCnup-1x8wBEiQAdw3OAdI71z-26qscYMnAjKHtgTmWMEfZ6ZjXWXVmGNE8PUMaAnp88P8HAQ
charge that via the dynamo and you will see what i mean as to how long it will take
http://uk.gpbatteries.com/uk_en/powerbank/f-series/fn03-1?gclid=Cj0KEQjwn_3GBRDc8rCnup-1x8wBEiQAdw3OAdI71z-26qscYMnAjKHtgTmWMEfZ6ZjXWXVmGNE8PUMaAnp88P8HAQ
charge that via the dynamo and you will see what i mean as to how long it will take
... A fair question deserves a fair answer . The SAdynahub, and it's more recent successors are brilliant devices. They have very low mechanical friction... Certainly compared with the bottle dynamo. They were able to produce about 6 watts of electrical power when cycled at a very high speed. They produced at a voltage 6v at 0.18amp to drive the two special bulbs, at normal speeds This is a load of about 2watts. . All this energy came from the rotation of the wheel. If you were to spin the wheel by hand say 1 push, and did not have the bulb connected, the wheel would spin and after a length. of time slow down and stop. If you pushed the wheel with exactly the same push, with the bulb connected, it would take less time for the wheel to stop. The reason the wheel slows is due to friction between the bearings and cones, the air resistance of the spokes . When the bulb is connected there is also a slight extra load due to the magnetic field created when current flows in the bulb reacting against the magnets in the dynamo..
As a youngster, you were energetic and could put maybe 150watts if power into the bike .. maybe 200 watts when you were sprinting. The extra loss of a couple of watts when the lamp was on was not really measurable.Most of the energy lost was to air resistance ,wind.
An electric bike consumes around 200watts. The amount being consumed at any instant depends on the load.. higher consumption when going faster or uphill less on downhill. The EU law allows 250watts. Even if one were to take the energy from a dynahub, increase its voltage from 6 to 38 V, and feed it into the battery, it would only be giving about 2 watts of power or 1% of the consumption. There would only be a value in doing so when one would otherwise be braking e.g going down hill. If one were to use this energy to charge the battery while on the level, you would either need to pedel faster or use battery power.
You might consider using a much more powerful dynamo, but that merely makes the numbers bigger. Don't change the principle
Most people have no idea about how large or small a watt is. We talk about a 2kilowatt kettle or heater and 100 watt bulbs. If you lift a 1kg bag of sugar, from the floor to the table, and take 10 seconds to do so, you have worked at a rate of 1 watt. Assuming table is 1metre, and standard bag of sugar.
My new ebike came with a hub dynamo for the lighting. I think that this is a good idea .. if the battery packed up, i would still be legal after dark.
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.. if you were using a 12v and 2a your power would be 24w. and it would take about 25 hrs . Nice video
Almost certainly! We've had a few of these recharge-while-cycling threads in here and have often been "informed" that technical advances will make it possible before long.
I call it subservient physics.
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Lets make it easy. look at that guy in Soundwave's video. He's pedalling hard. He's making about 130 watts output for about 200 watts of pedalling. it would take about 4 to 5 hours pedalling like that to charge up a 500Wh ebike battery.
That's without going anywhere. If you want your bike to move as well, you'd have to pedal with an extra 100w, which puts you up in the class of competition riders if you wanted to charge your battery in 5 hours.
The whole idea of an electric bike is to use stored electricity to help you to ride the bike so that you don't have to pedal so as hard as a non-electric one. What you're proposing is the other way round, i.e. to pedal harder than a normal bike to charge a battery. That doesn't make sense at all, unless, like in the video, you just pedal for exercise/training, and you don't want to go out on the dangerous roads.
That's without going anywhere. If you want your bike to move as well, you'd have to pedal with an extra 100w, which puts you up in the class of competition riders if you wanted to charge your battery in 5 hours.
The whole idea of an electric bike is to use stored electricity to help you to ride the bike so that you don't have to pedal so as hard as a non-electric one. What you're proposing is the other way round, i.e. to pedal harder than a normal bike to charge a battery. That doesn't make sense at all, unless, like in the video, you just pedal for exercise/training, and you don't want to go out on the dangerous roads.
a great answer Dan, i should have listened to my Physics teacher more closely,
probably this bit here is key looking back on it "As a youngster, you were energetic and could put maybe 150watts if power into the bike .. maybe 200 watts when you were sprinting. The extra loss of a couple of watts when the lamp was on was not really measurable."
Nobody,s mentioned solar power? Obviously not to enough to fully power an ebike? But suppose many have seen the YouTube clip about the lady doing long tour towing a solar panel the size of a decorators pasting table.
Yes, there's been many attempts and a few actually used. Best in Australia of course, with California a good alternative. Not so good in an average UK year.
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in theory, the sun gives us plenty more than needed to ride our bikes. The sun at altitude above the clouds, gives us about 1kw per square meter. On the ground, some is absorbed by the atmosphere but there is still plenty left from that 1kw/sqm. At the current rate of development, it won't be very long before solar cells can be made into fairings for your bike. When I got interested in solar energy, solar panel cost over $2/W. It's now less than 40c/W. £40 for a panel capable of recharging your bike while you are at work!
Do you want me to do a kickstarter project?
Do you want me to do a kickstarter project?
.. that would be nice as Mrs Brown says. To put numbers on it. The intensity is as you say about 1 KW per metres squared at top of atmosphere, and close to 800watt, peak value mid summer noon at our latitude. The efficiency of any commercial panel is touching 20% at present. So assume 160 watts at best. With inefficienices in power supply voltage regulator say 100w for the 4 hours bracketing noon. So it is feasible. The problem is if one is travelling , one has a big 1m2 panel catching the wind.
There are flexible film solar panels and these could be rolled up when traveling and extended during the off time. However these would not be as efficient I understand that 14% would be very good for that type.
Most people only need about 100WH-200WH a day to use the bike for commuting.
I was thinking of molding the flexible panels into mudguards, chainguard, baskets, rack boxes, triangle bags etc. and connect then together in the controller box.
Ideally, the cost of adding solar charging should be less than £100 all in. Depending on the situation, you could offset some of the cost of solar panels by having a lower capacity (thus cheaper) battery.
But all those figures depend on sunshine, and some years that's a rare commodity in the UK, especially in some regions. All too often we wake up to dull overcast skies, day after day seemingly for weeks.
Also a major use for e-bikes is commuting, done at the beginning and end of the day. So far from ideal for gathering sunlight, low sun angles blocked by buildings, other vehicles and foliage etc.
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Also a major use for e-bikes is commuting, done at the beginning and end of the day. So far from ideal for gathering sunlight, low sun angles blocked by buildings, other vehicles and foliage etc.
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