Yes that is right. A dynamo is a DC power source for your electrics and charges the battery is have one.
The dynamo should not give out 1-5v as that's to low.

As previous message has said that the dynamo most likely dying or damaged and most likely needs replacing. How old is the bike? Is if its quite old it will be a 6v system and if that is true that dyno needs to at least supply 6v-7v to charge a battery ideally.

Thanks for the info ! I will check again the voltages .

 

What does the manual specify? Can you post a link to the specification of the generator?

I don't have the specific manual

 

If you could measure the voltage and give a good value for that, particularly at a typical running speed, it would be helpful.

Thanks for your info

 

Yes. But before connecting the dynamo directly to the battery, install a rectifier diode in series to prevent a reverse current from the battery back into the dynamo. It that happens it will destroy your dynamo or kill your battery.

Look for a Schottky diode which is going to minimize the voltage lost across the diode. A 5A diode should be sufficient.

Perfect I am going to apply it then . Thanks !!

 

An alternator requires external power to drive current into the rotor windings.

While that is pretty much true in cars, most motorcycle alternators use permanent magnets instead of a field coil. That's the reason they also use shunt regulators too.

 

Is your bike the XTC or the MadAss version?
From what I gather, both have a Bosch 6V magneto-generator (i.e. AC output devices) with multiple generator coils, those for the lighting each having one end grounded.

 

It's a Sachs 125cc , no battery fited . I thought dynamo was an AC generator because of the headlights performance .

this has I think has a permanent magnet flywheel generator so NOT a dynamo
as the output will be AC and some of these small bikes only produce 30watts at 6volt
what wattage is your headlamp bulb

and from what you say its not producing enough volts/current to run the lights so trying to also charge a battery as well will not work.

 

Hello , I got a motorcycle (an old one) and I need to fix my headlights, because their lighting isn't powerful enough. So the dynamo - electric machine gives 1~ to 5~ Volts (5 Volts when I hit the gas too much) . As a result with 5 Volts , the headlights shines enough and I want to keep that light consistently . The problem is that I can' keep that light steady because, I don't hit the gas for ever .As a result the light's level is going down . I have tried changing my headlights with lower watt lamps and it kind worked , but I can't use lower wattage lamps for ever . Do you guys have any idea ? Will an amplifier that changes the ac to dc work ?
Sorry for my bad English and thank you so much for your time !

Sounds faulty to me. AC lighting is usually a grounded generator winding and any rectified supplies are half wave. If it isn't potted, you might be able to isolate the grounded end so you can feed a bridge rectifier. There are all sorts of problems - if there is a DC system, you'll have to re design that and probably add a regulator.