Transportation > Human Powered
Flashing LED Lights for Bicycle
hiker1:
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..😜
WooferHound:
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.
rossw:
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.
kurt:
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
frackers:
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
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!!
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