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 !

 

Welcome to AAC!

I think you need a voltage regulator and a 6V battery to power the headlights.

I don't know how the electrical system on your motorcycle works.
Here is how a typical 12V automotive system works.

The alternator produces an AC current that is converted to DC using rectifiers. The voltage is fed into a voltage regulator that prevents the voltage from exceeding a maximum voltage (about 14.5V). This is used to charge a 12V lead acid battery. The output from the battery is used to power the electrical system and headlights.

 

The only practical way to keep the lights bright is to add a battery to the bike, as MrChips stated, which also requires a rectifier to generate DC along with some sort of voltage regulator.

Are you sure the maximum generator voltage is only 5V?
What voltage are the bulbs rated for?

 

Welcome to AAC!

I think you need a voltage regulator and a 6V battery to power the headlights.

I don't know how the electrical system on your motorcycle works.
Here is how a typical 12V automotive system works.

The alternator produces an AC current that is converted to DC using rectifiers. The voltage is fed into a voltage regulator that prevents the voltage from exceeding a maximum voltage (about 14.5V). This is used to charge a 12V lead acid battery. The output from the battery is used to power the electrical system and headlights.

Thanks for your reply . So the output from the battery that u said is going to power both dynamo - electric machine and headlights right ? Also the voltage regulator will be placed between dynamo and lights , is that correct ? I appreciate your help !!

 

It depends on the what type of generator that is on your motorcycle. As I understand it, a dynamo does not require external power to operate because it has built-in permanent magnets. An alternator requires external power to drive current into the rotor windings.

The rectifier and regulator goes between the generator and the battery.
The lights are connected directly to the battery. Make sure that the lamps are designed for 6V operation.

 

The only practical way to keep the lights bright is to add a battery to the bike, as MrChips stated, which also requires a rectifier to generate DC along with some sort of voltage regulator.

Are you sure the maximum generator voltage is only 5V?
What voltage are the bulbs rated for?

Not 100% sure
They are rated for 6volt
Thanks for your help

 

If your motorcycle is an older model then it could have a dynamo and not a alternator. It most likely produces a DC current. You can use this to feed a rectifier diode and voltage regulator to charge a 6V battery, assuming that the dynamo output voltage is high enough to charge the battery.

 

It depends on the what type of generator that is on your motorcycle. As I understand it, a dynamo does not require external power to operate because it has built-in permanent magnets. An alternator requires external power to drive current into the rotor windings.

The rectifier and regulator goes between the generator and the battery.
The lights are connected directly to the battery. Make sure that the lamps are designed for 6V operation.

when you are talking about generator you mean the dynamo right ?

 

If your motorcycle is an older model then it could have a dynamo and not a alternator. It most likely produces a DC current. You can use this to feed a rectifier diode and voltage regulator to charge a 6V battery, assuming that the dynamo output voltage is high enough to charge the battery.

Perfect , so I will use dynamo to feed the voltage regulator in order to charge the 6V battery and from the battery output I will connect the motorcycle headlights , am I correct ? Really thanks for your informations .

 

when you are talking about generator you mean the dynamo right ?

Yes.
A dynamo is a DC generator.

 

Yes.
A dynamo is a DC generator.

Thanks for your help ! I will update this soon.

 

If your magneto/generator is making only 5V maximum its magnets may have lost a lot of their strength.
Adding a rectifier will lower the voltage available for the lights.
The voltage may be inadequate for charging a 6V battery unless the added regulator is a DC-DC boost type.
Bear in mind that one end of a magneto coil is usually grounded to the chassis, which means full-wave rectification would require isolating all the light sockets from chassis.

 

Perfect , so I will use dynamo to feed the voltage regulator in order to charge the 6V battery and from the battery output I will connect the motorcycle headlights , am I correct ? Really thanks for your informations .

Old motorcyclist here
what bike is it
do you already have a battery fitted?
The dynamo is DC and the bike should have already have a mechanical regulator fitted if you have a battery
you can convert most dynamos to 12 volt with an electronic regulator which means you can fit LED bulbs which take very little current for a Lot of light

 

Old motorcyclist here
what bike is it
do you already have a battery fitted?
The dynamo is DC and the bike should have already have a mechanical regulator fitted if you have a battery
you can convert most dynamos to 12 volt with an electronic regulator which means you can fit LED bulbs which take very little current for a Lot of light

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

 

If your magneto/generator is making only 5V maximum its magnets may have lost a lot of their strength.
Adding a rectifier will lower the voltage available for the lights.
The voltage may be inadequate for charging a 6V battery unless the added regulator is a DC-DC boost type.
Dear in mind that one end of a magneto coil is usually grounded to the chassis, which means full-wave rectification would require isolating all the light sockets from chassis.

Thanks for your info . I thought that dynamo was giving DC .

 

It depends on the what type of generator that is on your motorcycle. As I understand it, a dynamo does not require external power to operate because it has built-in permanent magnets. An alternator requires external power to drive current into the rotor windings.

The rectifier and regulator goes between the generator and the battery.
The lights are connected directly to the battery. Make sure that the lamps are designed for 6V operation.

Battery is going to charge from the dynamo with DC current right ?
I am new with these things and that's why I have so many questions !

 

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.

 

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

 

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

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

 

Battery is going to charge from the dynamo with DC current right ?
I am new with these things and that's why I have so many questions !

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.