I want to make a contactless bike dynamo, but need assistance.

[VooDooCC]

Warning: I'm incredibly new to magnets
I'm hoping to get a recumbent trike in about a month, which means I can't test anything yet. I've been searching all over the web for the past week or so for different dynamo designs. I've heard bad things about the bottle ones, the hub ones are just too expensive. Then I stumbled across this one from instructables and it looks simple enough, but possibly too simple. Would there be a better way to go, such as this one seems to be based on this?

For the first one, I have at least one old hard drive laying around I can salvage the magnets from. Would they be the best way, or should I order something else. How about coils? In the instructable, he used 600 ohm coils from old relays. Chances are I can find some old relays, but the same goes for that, is there something better I can order. Would more magnets get a higher voltage

For the second one, that price isn't bad, but would different magnets or coils be a little better? Wouldn't it be loud with the magnet flipping around all the time and hitting bumps in the road?

Things to consider:

• it'll be going on a trike, so not very high speed
• money is tight, so the cheaper the better
• i'll be powering front and rear lights, with standy, and would like to be able to charge a cell phone for gps (or at least maintain the current charge) The circuit shouldn't be too hard to figure out, but I need to make sure I can get the power.

[HairBear]

Very cool idea! I think you will have a lot of fun with this. You should be able to use just about any coil you might find. Use junk and try not to spend any money if you don't have to. Once you get a grasp on it, you'll be able to build one in minutes. All the parts you need can be found in everything from kids toys to old junk radios, tv's, or most everything electronic that people throw away.

Good luck and have fun!

[wrtner]

Yes, and if you are taking hard drives to pieces, there are some
very nice coils to be had near or on on the arm that moves back
and forward.

It should be possible to put a strong magnet very close to the path
of the spokes to magnetise the spokes as they pass, and the coils
will then take a charge off each spoke as it passes.

Don't forget to reclaim your back emf ! (He who wastes not, wants not)
A small rechargeable battery might be a good idea.

All this is reminding me of the Bedini SG.

[We.The.People]

To answer simply...

No contacts = stationary coils / moving magnets

With a full wave bridge rectifier on each coil to harvest
the magnets both coming AND going past of course...

But the one thing that may be the best advice,
is place the magnets just in from the rim itself
to obtain the highest velocity past the coils.

Straddle a pair of spokes with each magnet mount,
and consider coils on both sides of the wheel next.

And remember to chose spools of wires off the store shelf
that you can (also) see the inner end of the coil's wire too,
that way you don't have to wind anything in the first place,
just cut up some round ferrous rod that fits the core of them.

Hope these simple basics help you out somehow.


.

[kcarring]

just ideas

A few things to consider, ponder.. no real revolutionary concepts or proven stuff here, but:

1. The outside diameter of the rim (any spot on it) travels more distance, in the same time as a spot radial, on the hub. See Honeywell's new wind turbine (albeit ridiculously overpriced!!! Don't buy one, just check out the concept).

2. Read this document, it wont give you instructions but I guarantee you will learn a lot.


3. Consider a dynamo and a permanent magnet alternator COMBINED as seen in the VAWT built by MrDelanco on youtube. Mr Delanco takes the output of coil one, sends that energy into a dynamo, also driven, fires the DC component back into coil two (now AC+DC) and runs that in series with the rest of the coils. His output is ridiculously large considering the apparatus.

4. Consider having "fenders" wrap the bike rim, the rim holding the permanent magnets. you won't be able to go 360 degrees, obviously, but it is an idea of how to get more than one stator coil into action.

Good luck!

[VooDooCC]

First of all, thank you all for being positive and not just dismissing this.

Yes, and if you are taking hard drives to pieces, there are some
very nice coils to be had near or on on the arm that moves back
and forward.

It should be possible to put a strong magnet very close to the path
of the spokes to magnetise the spokes as they pass, and the coils
will then take a charge off each spoke as it passes.

Don't forget to reclaim your back emf ! (He who wastes not, wants not)
A small rechargeable battery might be a good idea.

All this is reminding me of the Bedini SG.

I didn't know if those coils would be at all adequate or not, wasn't sure if there's some value (impedance?(I haven't really done much electronics since school, but it should come back)) I should be looking for.
I never thought of trying to magnetize the spokes. I think my ponder is overfilling, lol.
What do you mean be reclaiming the back emf (we all gotta start somewhere) and I was definitely going to have a small battery of some kind. I have all sorts to choose from, including sub c nimh and 2s/3s lipo from when I was into radio control trucks.
Also, one of the links I posted was to the Bedini SG

But the one thing that may be the best advice,
is place the magnets just in from the rim itself
to obtain the highest velocity past the coils.

I was wondering if it would be better to have them farther from the hub or closer.

A few things to consider, ponder.. no real revolutionary concepts or proven stuff here, but:

1. The outside diameter of the rim (any spot on it) travels more distance, in the same time as a spot radial, on the hub. See Honeywell's new wind turbine (albeit ridiculously overpriced!!! Don't buy one, just check out the concept).

2. Read this document, it wont give you instructions but I guarantee you will learn a lot.


3. Consider a dynamo and a permanent magnet alternator COMBINED as seen in the VAWT built by MrDelanco on youtube. Mr Delanco takes the output of coil one, sends that energy into a dynamo, also driven, fires the DC component back into coil two (now AC+DC) and runs that in series with the rest of the coils. His output is ridiculously large considering the apparatus.

4. Consider having "fenders" wrap the bike rim, the rim holding the permanent magnets. you won't be able to go 360 degrees, obviously, but it is an idea of how to get more than one stator coil into action.

Good luck!

1. Are you saying the same thing, or opposite of wethepeople? Sorry, I'm still learning.
2. I'll give that a read, thank you.
3. That sounds a bit complex now, maybe version 2.0
4. I will have fenders, a rack, and seat stays since it's recumbent this site has some different examples.

Is there a ratio of magnets to coils that I should have?

[kcarring]

Is there a ratio of magnets to coils that I should have?

Yes. I mean, just about anything will generate some current; however, some typical arrangements are usually applied. Everything is relative to the -average rpm- that you feel the rotor will turn. Now, the rotor, being the part with the magnets, the stator being the part with the coils. Now in a DC generator, it's completely different.

Did you read the document by Hugh Piggot on permanent magnet alternator / axial flux alternators? You really should.

Then pick up a good read on DC generators. Get to familiarize yourself with the differences. In the wiki pages would be a great start.

You'll quickly learn a few things:

1. Your operating RPM is hugely important.
2. As you add a load to the alternator/generator a drag is created - is it so much that your RPM is affected? Is there cogging in your setup? Can it be reduced?

MY best possible suggestion to you is start with some background. You say you would like a touchless system, is that to save wear and tear on the tires' sidewalls for example? Because you do know, touchless or not, drag is imposed correct?

Also:

Given the style of bicycle you linked to, balance doesn't look like a huge issue, that thing looks like (I don't know of course, never rode one...) that you could almost drink a coffee and ride it.

If that is true, i would consider adding a drop down generator. In other words, instead of using a break, I'd have a lever, that dropped down under the seat. Manually operated perhaps, initially to keep life simple. Everytime you break, you charge batteries. Even on the flat, one must come to stops. Now out on long rides I guess that doesn't apply. The other thing I'd consider is a solar panel.

And I would use 18650 3000mAh (or better 4000 exist two) batteries here.
I pay about $3 ea. for 4000mAh batteries. If you have a lamp that uses a single 10 watt LED - it's bright and I mean BRIGHT. My driver runs it on 3.7V, And I give it 6-10 batteries, all in parallel. That 4000 mAH x 10. The LED takes about 2-3A depending on how hard you drive it. I use a PWM to control mine, so that I'm not wasting current to heat. All said even if u drive it full on, thats still over 10 hours of run time needed before charging. And I dont ride my bike for over 10 hrs at a time so im pretty good to go, BUT if I tried to ride across the country... I could see the need for recharging, on board.

If extensive need for power generation is there, and you really need power...
You might consider swapping one of those rims for a powered hub. When you want, have it powered, when you don't draw power from it... that might work nice too!

But when you do, make sure you bone up on your voltage regulation, you can't be charging those batteries with too many volts or u will damage them. If you want an elaborate very well working system, you'll need to proper disconnects. AS to not overcharge batteries - i.e. you think they're dead, but actually you are about to overcharge, so they "save themselves" unbeknown to you. The li-ions have disconnects inside the battery, but quite frankly i wouldnt rely on them; I think they are there for safety, a last ditch stop ofr current. Why be overheating that protection constantly.

If you get really into this let me know. If elaborate is what u need Ill pass a very cool circuit your way that is a maximum power point tracking IC circuit for lithium ions. Unlike voltage regulation, it waste very very little energy. It's pretty awesome, but not for the absolute beginner. It allows you to charge with too little voltage, too much voltage, whether from a dynamo, PMA, or the sun.

[VooDooCC]

For the RPM, it will be a 26" wheel, and average cruising speed of people with these trikes is around 10 mph, so if I did the math right, that would be about 129 rpm. This is on the very edge of the rim, and I would like to keep it at least a little farther away, so there's less risk of it catching grass or even bottoming out. I didn't bother with the decimals, as this is just an average, plus I used 26, so this would be an approximate rpm.

As for wanting the touchless system, I assumed it would give less drag than the sidewall type, plus I wouldn't have to worry about it slipping. Plus I should be able to rig this up for cheaper than the hub dynamos, and hopefully generate more power.

The trikes are very stable, and balance is only an issue when taking a corner at speed, just have to remember to lean. The problems with drop down system that I see is that the trike has 2 front brakes, and no rear, so it would lead to a lot of brake steer if the generator didn't slow the trike down fast enough. The other issue is that most of the riding I plan on doing is on bike paths and country roads, so not a lot of stopping.

I looked into solar panels, but was turned off due to price and reading a lot of people say that they do not yield much power, unless aimed correctly, which the trike would be constantly moving, and a lot of the bike paths near here are in shade.

I'm looking through the Hugh Piggot document now. I see that he uses 12 magnets and 10 coils, is this considered ideal for all, or is it based off diameter and rpm?

[theremart]

Contactless bike generator

freelights.co.uk

Already made. I bought one of these had alot of fun with it.

Mart