Phone charger using bike dynamo and Arduino buck module

[icecreamfan21]

Hi everyone, I've been thinking about creating a circuit to charge my phone while riding my bike. I've found this video and on another forum someone suggested using an Arduino buck step-down module instead of an LM7805. So in the end the circuit that I want to build looks like this:

My question is, would this work? I'm mostly worried about the current intensity in the circuit. On my phone adaptor it says that it generates 1A, so in theory the buck module should handle it, but I'm not sure how much the dynamo generates.

[jhaytera]

Might want to check how high your input voltage needs to be to produce 5 volts on the output of the buck step-down converter. Due to inefficiencies, 6 volts may not be enough. Just something I read once.

[bluejets]

Dead loss I'd say( for several reasons) ....output may be 6v but at a rather high pedal speed and from there you'd get around 8.4v peak at absolute best, which when rectified would bring you back to around 7v with diode losses. However the power output would be the killer at approx 3w whatever the calculation.

Some details on this site you may want to read.

https://pedalcell.com/en-au/blogs/blog/the-challenges-of-bicycle-powered-charging

Better to just throw a power pack in your back pocket.

[gilshultz]

Welcome icecreamfan21: Your question intrigued me but I am not a bicycle person. Out of curiosity I did a quick search and found this: https://www.ebikpro.com/bicycle-electric-generator-bike-riding-dynamo-dual-usb-interface-charger-for-phone-power-bank-cycling-scooter-parts-accessories-p-361137.html?gclid=EAIaIQobChMIgKvNkee4_gIVMhbUAR0_2Q_HEAQYDyABEgIQi_D_BwE I know nothing about this nor do I recommend for or against this, just posted it for information. My search term was "alternator for bicycle". Happy cycling!

[apf1979]

Could you put a 1:2 transformer to up the voltage output before the rectifier? Should still be in range but I'd test it.

[jremington]

As already pointed out, 5V at 1 Ampere is 5 watts, and the dynamo puts out only 3W, minus the considerable bridge rectifier loss.

[icecreamfan21]

I just checked the dynamo with a multimeter, I could get a little over 15V AC when I pedaled really fast, so the voltage should be well within range.

[icecreamfan21]

Thanks for the link! I was curious if I could build something like that from scratch I'm in Eastern Europe, so I think the shipping would be quite expensive. I'll try to find something locally.

[icecreamfan21]

Thank you everyone who replied! The parts are dirt cheap, around 5$ in total, so I'll just build it and see if it works. Will post an update when I'm done.