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What's the best way to add a battery like device to a dynamo light (self.askelectronics)

submitted 3 months ago by coke38 to c/[email protected]

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Hello everyone, I bought a bottle dynamo for my bicycle with a rear and front light. Though I have one little tweak that I would like to add and that's a way to keep it light up for about 1 minute (at least 30 sec) without pedaling. I thought of putting a capacitor in the circuit to store some energy but I would like what do you all think of it ?

Thank you for your time and have a nice day you all !

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[–] coke38 4 points 3 months ago (3 children)

I should have put the stuff I have, so here you are : Dynamo : https://www.axasecurity.com/bike-security/en-gb/products/lights/7/93903195SC/axa-hr-traction-right Rear light : https://www.axasecurity.com/bike-security/en-gb/products/lights/7/93929195SC/axa-juno-e-bike-6-12v-80-mm Front light : https://www.axasecurity.com/bike-security/en-gb/products/lights/7/92520095SB/axa-nxt-60-steady

Indeed it seems like a great project I think the output is DC though I'm not sure. To be honest I tried to put a capacitor (50V) put it seemed to had no effect (maybe to little capacitance or more probably the coil of the motor should have eaten the storage. Is probably should add a diode to the circuit, am I right ?

[–] [email protected] 3 points 3 months ago (1 children)

Excuse me if I'm wrong but the description of your front light says in the first sentence: "The AXA Nxt 60 is a dynamo front light [...] with a Steady light function allowing you to have 4 minutes of light when standing still. " Is that not already what you want?

[–] coke38 2 points 3 months ago

Really good point, though as a stupid human I didn't understood what was the difference between the Nxt 60 steady and the Nxt 60 E bike... Now I know. I don't have this marvelous option =\ explaining why the back doesn't light up either.... Thank you for pointing it out, I couldn't get the article from the site itself so I took another seller and it was not available (it is now)

[–] [email protected] 3 points 3 months ago (1 children)

If I'm understanding it correctly this generator has like wires out that then connect to the lights or something right?

If that's the case you'll need to see what kind of voltage it's putting out to those wires and then you would want to splice those wires into diodes to prevent the current from leaking backwards out of the capacitors. Then attach as many capacitors as you need for the voltage that it is providing, remembering that it is okay to have higher voltage ratings but not lower voltage ratings.

Chances are this will cause the light to be less bright as the capacitors are charging, so for the first few moments when you are riding it probably will be less bright but after the capacitors reach a steady charge you should see the light take a much longer time to dim down.

[–] coke38 2 points 3 months ago

Indeed, 2 pair of 2 wires so 4 wires can be connected to the dynamo.

I will try that, I need to find some proper diode then find the capacitor or buy it and I should be good. I'll keep you in touch if I manage to find the parts. Thank you

[–] [email protected] 1 points 3 months ago (1 children)

Your typical bike dynamo puts out 6V AC. I bet yours does as well, so that diode sounds like a good idea.

[–] coke38 1 points 3 months ago

Seems bad so, I have to make a diode bridge rectifier so =\ need to scrap more diode ! Too bad as I wanted to make something small