Dynamo battery charger

[JeanTech]

Hi there

I'd like to build a 9V dynamo battery charger. Can someone please send me a circuit diagram and an explanation.

Thanks in advance

 

[louishenri]

Help......

Hi there

I'd like to build a 9V dynamo battery charger. Can someone please send me a circuit diagram and an explanation.

Thanks in advance

hi i also would like to know how to build a 9v dinamo charger let me know when you have the info.

 

[Hero999]

You haven't provided enough information: you need to tell us the capacity of the battery and the current and voltage rating of the dynamo.

 

[Boncuk]

To get 9V out of a bicycle dynamo you must work real hard (approximately 60kmh).

Why not charge a 6V battery at moderate speeds?

 

[Hero999]

If it's a bicycle dynamo then it most likely isn't a dynamo but an alternator.

The peak voltage is 8.5V so you might be able to charge a 9V battery if you work really hard and use a Schottky rectifier especially if it's really a 7.2V or 8.4V battery.

 

[JeanTech]

The battery specs is 9v but the current doesn't have to be specific. It must just be sufficient to power a 9v radio. Is it possible to step-up the 6.2v to 9v?

 

[Hero999]

You still haven't answered my questions above.

Do you want to charge a 9V battery or power a radio or both?

A 9V radio should work from 6.2V but you might not be able to turn the volume up as much without it distorting as you would be with a 9V power supply.

Of course assuming this is 6VDC, not 6VAC which will probably destroy the radio.

 

[JeanTech]

hi there

the dynamo should just charge the battery. I'm thinking of using a 3W 6V dynamo. is there a schematic I can use to see how to connect everything together?

Thanks for the help
JeanTech

 

[Hero999]

Going on my assumption that it's AC not DC, here's how I'd do it.

 

[JeanTech]

Going on my assumption that it's AC not DC, here's how I'd do it.

thanks very much, this circuit will work perfectly!

 

[Hero999]

It won't work if it's DC.

I suggest you measure the output voltage from the generator.

Fortunately, it won't do any harm, if it's DC the battery will just fail to charge.

 

[JeanTech]

Assuming the dynamo outputs 6vdc, what should I change in the above circuit?

Thanks in advance

 

[Hero999]

The circuit will be much more complicated, if the voltage is 12VDC.

I think you should make sure you know whether it's AC or DC first.

If you're not sure, connect two LEDs in reverse parallel with a 470R resistor in series and connect it to the output of the generator. If it's DC only one LED will glow, if it's AC they'll both glow.

 

[JeanTech]

Is it possible to use a motor instead of a dynamo? Then you could just turn the motor, and as far as I know, my motor outputs ac when turning.

Also would it charge a 9v battery if it only gives 6v or 3v power?

 

[Hero999]

You could use a motor.

A DC motor will output DC and a stepper motor will output AC.

The motor will need to output a higher voltage than the battery plus a diode drop, to charge the battery.

 

[JeanTech]

Assuming I use a bipolar stepper that outputs 3vac, would the circuit you posted earlier on charge a 9vdc batt, if not, what can I do?

 

[Hero999]

Then you'll need a voltage quadrupler to charge the battery and it presumably needs to be be multiphase too.

It's easier to use a 6VAC generator.

 

[JeanTech]

I'm new to electronics and would like to know, how can a 6vac motor/generator charge a 9 vdc batt?

 

[ericgibbs]

I'm new to electronics and would like to know, how can a 6vac motor/generator charge a 9 vdc batt?

The circuit post #9, by hero, is a voltage doubler.

 

[JeanTech]

Hi Eric

thanks for the help, it makes sense now