moped lights

iveco_man

Does any body know why when i run my moped the side lights are dim when i rev it they get bright and when head lights are on the same happens but the tail light stays dim ...many thanks in advance. :huh:

forgotmyname

Battery voltage is low. Alternator voltage is also low at low revs.

Increasing the revs increases the voltage.

Richard53

What's the moped? If it's an older model, it's likely to be a magneto rather than an alternator. In general terms, the ignition and extra loads such as lighting are run directly from the magneto, and the tiny battery is only there to make sure the lights don't go out completely when you stop.


It's a feature, not a bug. Every small bike I have had (Honda Cubs etc) has done this.

BillJones

As above, it's down to the bike not generating enough voltage at lower revs. A new magneto/alternator might help things a bit, and if you've an old battery, a newer one that holds charge better may also help, but on some models, this is just how they are.

You could look at different bulbs, maybe see if there's an LED one that puts out more light than the standard one, and can charge the battery while the bike's at home, but some smaller capacity (and especially older) bikes simply come with electrics that only just do the job in absolutely ideal conditions, and struggle otherwise.

Norman_Castle

Removing the rear light lens and cleaning the bulb, reflector and inside the cover may help. Checking the wiring connectors, including earths connected to the frame, for corrosion may also help.

Richard53

Good advice if the lights are dim all the time. But I think the OP's question was why they dim when the engine slows down and get bright at higher revs. The answer's in the voltage - magnetos tend not to be as well-regulated as an alternator.


As an example, on my very first bike, a Honda C70 (yay!), the headlight was like a glow-worm at idle, about equivalent to a 5W pilot bulb. On the other hand, with the engine maxed out down a long hill, the headlight bulb would frequently get as bright as the surface of the Sun, and then blow.

Norman_Castle

Good advice if the lights are dim all the time.

Apparently the tail light is dim all the time. There are two questions, variable lights and permanently dim light.

the tail light stays dim

As an example, on my very first bike, a Honda C70 (yay!), the headlight was like a glow-worm at idle, about equivalent to a 5W pilot bulb. On the other hand, with the engine maxed out down a long hill, the headlight bulb would frequently get as bright as the surface of the Sun, and then blow.

Thats possibly caused a faulty regulator. I had similar with the tail light of a small bike. "Solved" by using a 12v bulb on a 6v bike.

iveco_man

Norman you are correct on side lights tail light is good but when on main lights dipped or main the tail light goes dimmer on all revs

Norman_Castle

I would check for poor or dirty connections. On side lights there may be enough excess current to bridge a poor connection.