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Transportation => Human Powered => Topic started by: WooferHound on May 13, 2018, 08:01:32 am

Title: Flashing LED Lights for Bicycle
Post by: WooferHound on May 13, 2018, 08:01:32 am
The severe cold this last winter froze the engine in my van and I have converted completely over to bicycles to get around town for awhile. Am using a 50 year old Schwinn 10-speed as my main bike and just rebuilt an 18-speed Roadmaster as a backup bike for the occasional flat tire. Pedaling about 2.5 miles downtown to work which only takes me almost 15 minutes. While I am riding I have plenty of time to dream up improvements to make the ride safer and more comfortable. I would really like flashing LED lights all over the bike powered by the spinning wheels.

So the current idea is to attach a magnet to the spokes of the rear tire, then mount a coil on the frame where the magnet passes. This would flash the lights once everytime the tire rotates. Tried to make a test setup last night and it did not work as well as I thought it would.

The coil was a factory air-core choke with about 150 turns of very fine wire, maybe 26 gauge, and measures 1.6mh, it is about the diameter of a dime and 1/4 inch thick. The LED was a 2 volt red soldered directly to the choke without any resistor.
I started out with a magnet the size of a Quarter,  passing it by the coil  by-hand as fast as I could without any light produced. Then tried a 1 inch stack of magnets about the diameter of a nickle and still could not produce light. So I tried to use an 8 inch stack of 2x2x1/2 magnets leftover from building my small Wind Generator and produced some barely noticeable strobing  made from the fastest movement.

I really thought this would be enough to flash some LED lights.
What would be the best way to make this work ?
Was also thinking about using a Bridge Rectifier with it's voltage drop to extend the length of the flash and would probably need some kind of current limiting because of traveling at different speeds.
Title: Re: Flashing LED Lights for Bicycle
Post by: Wolvenar on May 13, 2018, 08:45:46 am
I get the DIY aspect, but with the cost of these super bright high visibility safety lights anymore, it's just easier and cheaper to grab a rechargeable super bright one online or from Walmart. ..

But, if you are still going to DIY.. I would rectify the output, add a cap to hold the charge for a tad longer on time of the LEDs.
Then add a proper resister and zener diode to limit the maximum voltage so it is predictable, use identical LED(s) in parallel if more than one and add the proper resistance to limit the current.

This is all with the assumptions you can get enough power from that setup, and that you want the LED to flash on for a short time only at the occasions it can source the power each time the magnet(s) come around from the wheel.
Title: Re: Flashing LED Lights for Bicycle
Post by: noneyabussiness on May 13, 2018, 12:50:30 pm
Maybe try a non-polarized capacitor parallel with led.. but im with wolvenar , i doubt you will get enough juice...
Title: Re: Flashing LED Lights for Bicycle
Post by: MadScientist267 on May 14, 2018, 01:48:06 am
The coil is the main killer.

Air core has the least concentrated flux... You could stack those magnets until you're blue in the face, it's gonna be a diminishing ROI if the magnetic circuit isn't tight enough.

Achieving that isn't quite what it appears by simply "flipping an axial PMA inside out" with 1 magnet and 1 air coil (or even one on each side).

In an axial PMA, the flux is tightly controlled by the discs and magnets themselves, causing it to "beam across" the gap, which significantly offsets the inefficiency of the air core. In a situation like the bike, the flux is dilute and "flairs" out as it leaves the poles... maybe "aimlessly" is a decent word. Closing it up (look at the brakes for an immediate visual on my kneejerk thoughts) will help tremendously.

That's also an awful physically small coil. You're cutting the turns with a much larger diameter "slice of flux" than the coil, which just further dilutes it's potency and with that kind of difference in diameter, probably is even causing self-canceling effects. An air core coil doesn't have any means of directing the flux thru the center so it cuts more efficiently, so this won't work.

One more thought comes to mind for when it's on the bike... the rim, being steel, is going to also steal some of the flux and short it out... difficult to work around since you can't put a pair on either side even to gain a useful pole out of them, because of the brakes.

This is one of those "what works in the classroom needs performance tweaks before it's useful in the real world" deals. If you were looking to read RPM, I'd say you're on a reasonable path, sorta... Any kind of real power, no.  :-\

Steve
Title: Re: Flashing LED Lights for Bicycle
Post by: Pete on May 14, 2018, 07:16:31 pm
Hi Woof, a lot of small engines have a charging coil on them to charge their starting battery if they are electric start. You could get one of those coils and use it to run the LED,s. It does seem that a small rechargeable commercial light would be easier, but then easier is not so much fun is it.
You could also just try getting a piece of steel and winding your own  core on it. You are only looking for low current and low voltage after all.

Pete
Title: Re: Flashing LED Lights for Bicycle
Post by: WooferHound on May 18, 2018, 10:36:49 am
I guess I had forgotten how hard it is to make useful power.
Now i am thinking I need to try and make a small magnetic circuit with 2 magnets and a U shaped piece of metal to carry the flux between them and through the coil.
Already starting to worry that the magnets will unbalance the tire. Want to avoid any iron cores so no energy is taken away from the rolling bike.
Title: Re: Flashing LED Lights for Bicycle
Post by: WooferHound on September 25, 2018, 08:09:51 am
I have a lot of time to think about it while riding the bike and I believe the solution isn't magnets & coils. It would be so easy to make Solar Bike Lighting. I might even have everything I need here already. Might want to get a battery specific to the purpose. Could start with a Solar Yard Light and work from there.
Title: Re: Flashing LED Lights for Bicycle
Post by: hiker1 on September 26, 2018, 11:03:12 am
Stopped in a my local Home Depot..they had large hooded solar yard lites for a buck eighty...took one home ..let it charge all day...nice bright flood lite..burned all night...thought about hooking to bike as well....😜
Title: Re: Flashing LED Lights for Bicycle
Post by: hiker1 on September 26, 2018, 11:08:12 am
Should have grabed a few more..end of season sale..ILE buzz back ...pick up a few more..?
Title: Re: Flashing LED Lights for Bicycle
Post by: WooferHound on September 28, 2018, 08:59:20 am
Stopped in a my local Home Depot..they had large hooded solar yard lites for a buck eighty...took one home ..let it charge all day...nice bright flood lite..burned all night...thought about hooking to bike as well....😜

That is too cool, almost perfect to add directly to the bike.

[attach=1]
I am going to make my Bike Lights from this Solar Garden Accent Lighting unit. In this picture I have pried the unit apart and you can see both the front and the back. Also disassembled a computer battery pack and got six 18650 Lithium batteries that are rated 3.6 volts at 2600 mah. The one in the picture has been running a Red & White LED for 12 hours.

The plan is to cut out the AA battery holders to make room to glue in the larger Lithium battery. The Solar panel measured 4.75 volts in full Sun so I should be able to put a diode inline so the battery will charge up to 4 volts. There will be a toggle switch on the handlebars to control it. There will be 10 LEDs total: 2 white facing forward,  2 white facing the road over both tires, and 4 red in a square pattern facing the rear. Fairly Tricked Out and very visible.
Title: Re: Flashing LED Lights for Bicycle
Post by: hiker1 on September 28, 2018, 05:35:05 pm
Nice...post a few pics when mounted..the lights were sold out when I went back...dang...I new I should  have picked out a few more...thought maybe they were defective..at such a low price...😜 haven't built any gens in awhile...have a few ideas about another bike gen...never ends..😜
Title: Re: Flashing LED Lights for Bicycle
Post by: WooferHound on October 02, 2018, 04:56:36 pm
This project is coming along, mostly testing right now.

Open Circuit, the panel measures 4.75 volts at .125 ma.
Hooked the Solar Panel to a 1N4007 diode then to a 18650 Lithium battery.
Target charging for a lithium battery is 3.9 - 4.1 volts.
My battery was getting up to 3.5 volts. Was wanting more than that so I fished around and found a Schottky diode with a smaller voltage drop. Soldered that on there today and placed it back out in the Sun today to see if it bumps the voltage up a coupla points. As soon as I see how high the voltage gets with the Low Loss diode, I will do the calculations and order the LED-resistors for for this project and plenty more.

Have also cutout the backpanel for the battery. I already have all the Wire, LEDs, power switch and other stuff to put it all together. Current plans are to have 12 LEDs running totaling 240ma.
Title: Re: Flashing LED Lights for Bicycle
Post by: rossw on October 02, 2018, 05:18:19 pm
Woof, I don't wish to pick on you ... but cripes, can you check your work??

Firstly. you can't have a current flow into an open circuit.
Next, 0.125mA seems waaaay too low. Certainly too low to be any practical use.
If your LEDs are drawing 240mA, it would take you 80 WEEKS of uninterrupted full sun to charge your battery up enough for 1 HOUR of operation, at 0.125mA. And over that timeframe, the self-discharge would eat most of it up anyway.

1N4007 or even schottky diodes at those voltages are hideously inefficient. A tiny P-channel mosfet off ebay will cost you less than a 1N4007 diode, and when wired as an "ideal diode" will have virtually no voltage drop in this application.
Title: Re: Flashing LED Lights for Bicycle
Post by: kurt on October 02, 2018, 06:08:19 pm
those batteries from the laptop pack are lithium cobalt batteries they really do not like being charged by anything other than chargers specifically designed for them and they have a tendency to get angry and explode and spit fire that will not go out when abused google lipo fire there are allot of videos of it. i would suggest spending a couple bucks and buying a few batteries of a safer chemistry to play with

might i suggest a couple of those aa size lifepo4 cells with built in over voltage and over discharge protection  be much safer
Title: Re: Flashing LED Lights for Bicycle
Post by: frackers on October 02, 2018, 06:26:01 pm
I'd recommend one of these between the solar cell and the lithium cell
https://www.aliexpress.com/item/5V-1A-Micro-USB-18650-Lithium-Li-Ion-Battery-Charging-Protection-Board-Charger-Module/32809897126.html (https://www.aliexpress.com/item/5V-1A-Micro-USB-18650-Lithium-Li-Ion-Battery-Charging-Protection-Board-Charger-Module/32809897126.html)
Its what I used on my weather station and apart from 1 week in the middle of winter has provided 24/7 charge from a 1w 6v panel for over a year now.
Almost the same price as a diode!!

Title: Re: Flashing LED Lights for Bicycle
Post by: WooferHound on October 03, 2018, 11:25:56 pm
Woof, I don't wish to pick on you ... but cripes, can you check your work??

Firstly. you can't have a current flow into an open circuit.
Next, 0.125mA seems waaaay too low. Certainly too low to be any practical use.
If your LEDs are drawing 240mA, it would take you 80 WEEKS of uninterrupted full sun to charge your battery up enough for 1 HOUR of operation, at 0.125mA. And over that timeframe, the self-discharge would eat most of it up anyway.

1N4007 or even schottky diodes at those voltages are hideously inefficient. A tiny P-channel mosfet off ebay will cost you less than a 1N4007 diode, and when wired as an "ideal diode" will have virtually no voltage drop in this application.

Yes, a significant typo there. That solar panel produces 125ma (short circuit) at 4.75 volts. But after today, charging through the Schottky diode the battery only gets up to 3.6 volts, which is fine for my uses. In my discharge tests, these 18650 batteries have great power between 3.7 and 3.2 volts. The 240ma bike lights could run more than a couple of hours after beeing charged up to 3.6 volts, plus safety when charging and using these lithium batteries up to 3.6 at .125 amp is almost guaranteed.

And yes you are also correct talking about how difficult it is to work with voltages between 2.6 and 4.2.
Title: Re: Flashing LED Lights for Bicycle
Post by: WooferHound on October 05, 2018, 04:58:53 am
those batteries from the laptop pack are lithium cobalt batteries they really do not like being charged by anything other than chargers specifically designed for them and they have a tendency to get angry and explode and spit fire that will not go out when abused google lipo fire there are allot of videos of it. i would suggest spending a couple bucks and buying a few batteries of a safer chemistry to play with

might i suggest a couple of those aa size lifepo4 cells with built in over voltage and over discharge protection  be much safer

Yes Kurt, you are very correct that charging Lithium batteries incorrectly can be Fire and Death ! !

However I have spent some hours reading about Lithium 18650 charging, plus I have become a "YouTube Expert" on the subject.

The Key Points are . . .
Do Not Exceed 4.2 Volts or there will be Fire
Do Not Discharge Below 2.5  Volts or you will damage the Cell
Do Not Charge or Discharge the battery faster than Half of it's capacity
Do Not Short-Curcuit or there Will be Fire
Use Balanced Charging. Lithium Batteries in Series do not remain Equally Charged and must be Maintained Individually to keep the Charge Equalized
It is also good to keep them Cool as possible and Protect them from Physical Damage

So if you are only using a single 18650 battery, with low charge/discharge currents, and stay between 2.6 volts to 4.1 volts (hard limits), you will have a lovely experience.
It acts much like a large capacitor and as long as you watch the voltage limits it is a happy playground to play in.
I built a Dual 18650 charger using a 6 volt centertapped transformer, very few parts and charges the batteries up between 4.0 & 4.1 volts over a 6 hour period.

Title: Re: Flashing LED Lights for Bicycle
Post by: WooferHound on October 06, 2018, 06:53:09 am
Did a Discharge test yesterday. Started with an almost full 18650 battery. Connected a 15 ohm resister making a 250ma load which is the same load as my lights would make. Checked the voltage every hour and noted it down

4.04
3.94
3.84
3.74
3.65
3.60
3.57
Sleeping
3.45
3.40
voltage rapidly declines at this point and it does not take long to get down to the 2.5 volt limit

So most of the power appears between 3.7 and 3.4 volts. My Bicycle Lights would work well for 5 hours with a charge of 3.6 volts.
At home the bike is parked outside, in some bushes around the house and the solar panel would get Full Sun a couple of hours a day which should be plenty. I would use the lights for about an hour a week riding at night, usually about 20 minutes on late rides home from work.

Was also thinking about adding a connector for attaching accessories, like Christmas Lights or a small LED Spotlight, maybe an MP3 player or something. Would also use the connector for checking the battery voltage. Wondering how to do that and stay weatherproof?

Made a Order to Parts Express for the LED resisters using 3.6 volts as the source voltage, 82 ohms for Red and 33 ohms for White. Also ordered some 56 ohm resisters for White LEDs on a 4 volt full charged battery.  Also have some 18650 Battery holders coming for some future projects.
Title: Re: Flashing LED Lights for Bicycle
Post by: WooferHound on October 10, 2018, 05:24:48 pm
Getting almost done on this Bicycle Lighting project

[attach=1]
Took the Front Reflector off of the bike and epoxy glued 6 white LEDs to the back of it. The dropping resisters were included to make the wiring work out better. This is all of the LEDs for the Front of the bicycle. Top two will be aimed Far Field, middle LEDs aimed Near Field. The Bottom LEDs have had the lens on the front ground flat so they throw a wide beam, and they will be aimed straight down at the road. I have tested this a few times with a stand-alone precharged battery and it works wonderfully.

[attach=2]
This is the front & back of the Solar Panel. I glued some aluminum foil to the back of the front panel to help reflect the heat away from the battery. There will be 8 LEDs placed all over the back of the bike, 4 white pointed down at the road, and 4 red pointed to the rear of the bike. All the LED Dropping Resisters are inside the inside this box so they won't be exposed to weather outside. A phone wire goes to the front for a negative connection and a power switch on the handle bars. All 8 LEDs will have a pair of wires going to each one.

[attach=3]
Here is the Solar Panel assembled and ready to install on the bike. There is a 1/8 inch connector that supplies unswitched power direct from the battery. Thinking about epoxy gluing the LEDs into their final position. Total of 14 LEDs: 4 white forward, 6 white wide angle pointed down at the road, and 4 red wide angle pointed to the rear, making a total of .280 amp.

Working for a few days so may be awhile before this is finished.
Title: Re: Flashing LED Lights for Bicycle
Post by: hiker1 on October 22, 2018, 10:34:25 pm
Your all lit up..now for sound...here's my little solar powered radio..old Sony ..bike radio...used one of my solar lawn lite..for power..it has one fat 3.5-4v batt built in..perfect for my 2 cell radio...
Title: Re: Flashing LED Lights for Bicycle
Post by: WooferHound on January 10, 2019, 08:10:34 am
Unfortunately my Bicycle was stolen last week. It was hiding it behind some bushes in front of the house, but somebody knew it was there and got it. I had a lock on the bike but wasn't using it.

I had installed the Solar panel onto the back of the bike and had working lights in the front for a coupla months. Had wiring installed for the Tail & Marker lights but had not installed the LEDs yet so wires were sticking out everywhere. The night before, I had worked on the front axle and put it all back together without grease or oil. The rear brakes had just stopped working. While it sucks to lose that bike, I am happy that it was in poor condition when they got it. Originally purchased at a garage sale for $25, but had $75 of puncture proof tires and $50 baskets on it.

The stolen bike was a 27 inch Road Bike and not made for the Inner City riding that I am doing almost daily. On Craigslist I found a 26 inch mountain bike with Road Tires on it, Perfect for jumping curbs and fast speeds. It was an older bike but has lots of New working parts on it, plus the guy gave me a buncha spare parts and a pair of innertubes. Got it for $150 and rode it 2 miles home. I've installed bike locks in it's parking spot behind the bushes and plan to put Motion Detector alarms in the area too.

So now it's time to Trick Out the new bike with Solar lighting, Saddlebag baskets, and a Bike computer speedometer. The baskets are on order and I've picked out a fancy bicycle computer that has a thermometer on it.

The Solar Lighting looks like it will be much easier to make now that Solar Charged Power Banks are cheaply available on eBay. I have ordered this one that can hold a couple of 18650 batteries and supply a constant unswitched 5 vdc output ...
https://www.ebay.com/itm/2W-Solar-Panel-Charger-for-1-2-Section-18650-Battery-Phone-Charging-Charger/312419337228
This is almost already made compared to the one on the other bike. Will need to weatherproof it a little bit. Has plenty of room for the minimal electronics that will need to be added. Plus it can charge my phone too.


Title: Re: Flashing LED Lights for Bicycle
Post by: WooferHound on February 01, 2019, 03:00:29 pm
Today, I received the Solar Powered USB Power Bank that I had ordered a few weeks ago.

[attach=1]

Tested it a bit and in almost Full Sun the panel puts out 6 volts at a short circuit current of 350ma, so about 2 watts

[attach=2]

The Solar power goes through a diode straight to the battery and if left alone it will badly overcharge the battery. Have some 4056 charge controllers ordered to fix this problem.

[attach=3]

It will hold 1 or 2 batteries in parallel. One 18650 battery is plenty to power the planned bike lighting for about 6 hours, So I'll only use 1 in there. I tested the 5v USB output and my phone will charge from it. But that little boost converter will probably be removed as it isn't needed.
Title: Re: Flashing LED Lights for Bicycle
Post by: bj on February 02, 2019, 06:50:25 am
  You've got mail
Title: Re: Flashing LED Lights for Bicycle
Post by: WooferHound on February 12, 2019, 10:33:35 pm
I was waiting for the TP4056 Charge Controllers to arrive before finishing the Solar Bike Lighting, Then they got here while I was working a large show over the weekend. But today was a day off so I finished out the power box then installed it all on the bike.

[attach=1]

First pic is the Power Box fully finished but without the solar panel cover.
The blue module (top right) is the Lithium Ion 18650 charger module. it also has over\under charge protection on it.
The battery compartment is covered with aluminum foil to help reflect heat away. It can hold 2 batteries but only 1 should be plenty.
The 2 power switches are on the far left, very small and hard to see. One switch is for the white Headlight, a 1w LED at 300ma. The other switch is everything else, 14 LEDs all over the bike, about 300ma in all.
The small terminal strip on the far right is the Switched power. All LED dropping resisters are here and connect to the outgoing wires.
Four of the LEDs are in the power box too.

[attach=2]


When completed there will be 4 Red LEDs across the back, 6 white LEDs in pairs pointed down at the road, 2 yellow LEDs facing out to each side, plus 4 Fast Color Changing LEDs over the headlight to get attention.

[attach=3]

The wiring has been run up-front to the headlight area but has not been finished yet. I've been working on it and will have some more pictures of the completed project soon.
Title: Re: Flashing LED Lights for Bicycle
Post by: WooferHound on February 13, 2019, 05:02:03 pm
A few points that I should make ...
All the small 5mm LEDs have the Lens ground flat and are wide angle, not the normal 9 degree LEDs
The positive contacts in the battery compartmentl were too short making battery contact difficult, but a blob of solder on there fixed it
I glued shiny foil to the back of the solar panel to help reflect heat coming from the panel

[attach=1]

This morning I wanted to test if the panel was charging the battery.
Battery was Discharged down to 3.64 volts. Bike was placed in the light optimized to the Sun
In 4 hours it had charged up to 4.14 volts. I can't see the -Charged- light on the charger module but this should be about Full Charged ... So it is charging.
The solar panel is capable of a max charge rate of 300ma. All the lights on the bike add up to about 650ma, and used for an average of  45 minutes a day. It will almost never get great light. However I think the solar charging will be able to keep up with my expected usage.
Fortunately the batteries are easily accessible and if the charge gets too low, a fresh battery can be put in there quickly.

[attach=2]

The planned lights on the front of the bike include the White Headlight, 4 or 5 color flashing LEDs, and 2 white lights aimed down at the road. I want to spend some time on this and have installed some quick-n-dirty temporary lighting for now.

[attach=3]

Since a 1w LED Bead light is so small and bright, it is hard to look at directly, so it's a good idea to keep the direct it away from oncoming traffic. This Romex Connector was perfect to control the beam and keep the light away from oncoming drivers. Some Color Flashing LEDs were glued on top to make sure that I get noticed.