Powering dynamo lights from a remote battery?

[GrasB]

Anyone done this? Did it work well or did you have problems? To me it seems like a relatively cheap source of shaped beam from lights & bright but not too powerful rear 'judge by' lights (to supplemented with a brighter battery powered light for attention grabbing flashing at night/day time riding). I also don't need to worry about voiding warranties by modifying quite expensive lights to have connectors I can make up cables for.

 

[Biker Joe]

I have done this, all be it a long time ago.
I was fed up with the resistance caused by the dynamo They were not as efficient as modern dynamos then.
I used a 6 volt lantern battery stashed inside my saddle bag.(That tells you how long ago that was.)
I later made a container that was strapped to the cross bar.
It worked well.
I eventually managed to get a hub dynamo which I stayed with for a number of years.
Today, lantern batteries can be bought for around £2 to £3 pounds at the lower end which have around 1100 ah. Alkaline batts have around 1300 ah but cost around £5 or more.
I wouldn't do it now though. Modern cycle lamps are so much more powerful.

 

[Rohloff_Brompton_Rider]

As the generator (correct term) is 3w 6v and I assume its modified output is dc, it's not different to adding a 6v cell.

 

[Rohloff_Brompton_Rider]

I used to have a 3w BB dynamo connected via a bridge rectifier to some lead acid batteries to power some ridiculously powerful halogens. I had to charge the batteries every now and then in winter, when the dynamo output failed to keep the batteries topped up.

 

[andrew_s]

The instructions for a B+M IQ Cyo say the following about use with a battery:

If you connect the headlamp to a rechargeable battery (entirely at your own risk)
make sure to observe correct polarity, i.e. "plus" to the earth inlet and "minus" to
the current inlet. Maximum brightness is obtained at a voltage range between 7.2 and
7.5 V (7.5 V must not be exceeded)

As the generator (correct term) is 3w 6v and I assume its modified output is dc, it's not different to adding a 6v cell.

A bicycle hub dynamo is not strictly 6V 3W. It's closer to a 0.5A current source, and the voltage can go a lot higher than 6V, depending on load and speed.
It also generates AC, so a rectifier will be built in to any LED cycle light.

 

[snailracer]

http://www.pilom.com/BicycleElectronics/BicycleElectronics.htm

 

[Rohloff_Brompton_Rider]

The instructions for a B+M IQ Cyo say the following about use with a battery:



A bicycle hub dynamo is not strictly 6V 3W. It's closer to a 0.5A current source, and the voltage can go a lot higher than 6V, depending on load and speed.
It also generates AC, so a rectifier will be built in to any LED cycle light.

That's why I said modified, I don't know if they're rectified and voltage regulated within the hubs these days or if the regulating and rectifying is done in the light.