philski

I have an older bike with the classic headlamp/taillamp/generator operating at 6V. It works but the generator is a huge drag and going up hills I sometime lose light. I'm thinking about using a 2S lipo pack (7.4V) to power the lights with the generator off.

Anyone run old 6V lights off of 7.4V? Are we looking at severely reduced lifetime of the bulbs? If so I guess I need to build a 6V regulator.

Or are there other bulbs I could use to avoid the regulator?

thanks,

philip

siberia37

7.4V->6V might be a bit of a problem for the typical Buck Switching regulator. Usually they need around two volts above the regulation voltage. You could use a linear regulator but it will be inefficient. Also remember if your using Lipo you need a cutoff circuit, so it gets even more complicated. The best solution might be to try a more modern bottle dynamo like the Busch and Muller or Spanniga, or rebuild the wheel with a dynamo hub and trash the old bottle dynamo.

philski

RC hobby cutoff regulators are real cheap. The voltage regulator, yeah, I was trying to avoid it. But thanks.

philip

Burton

NiteRider was actually running 4.8V bulbs in their 6V systems so if you're willing to accept a reduced bulb life, it'll probably be OK. Can't suggest bulb alternatives without knowing what bulb base type you have.

And Lithium batteries need a special recharger so before buying a battery and charger, suggest you see if you can't get better light output cheaper simply by upgrading the entire light.

philski

This is an old school bike lamp set they use the traditional bayonet bulbs.

I have a LiPo charger. I'm fairly familiar with them, using them in RC helicopters and planes.

I'm avoiding upgrading the light fixtures to preserve the look of the bike - if there is a LED or halogen retrofit kit for classic bike lamps, I'm all ears!

philip

whitefiretiger

depending on the lights you have and your tenkering skills you could do something like i did.

https://www.bikeforums.net/showthread...LEDs?highlight=

philski

Interesting idea, thanks! The back light is very flat I don't think I could fit a flashlight unit inside. But it is something to think about, with all the cheap knockoff Chinese torch lites you can find online there may be something managable. Thanks for the idea.

whitefiretiger

i used a book light for my tail light because it was too small to fit anything bigger.

i used this and cut extra plastic off to make it fit and replace\d the clear led with a red one

oh and i fixed all the broken pics in that thread.

bicyclridr4life

If it is a standard flashlight type bulb, Home Depot (or was it Lowe's?) has a 1 watt LED conversion bulb that works with 2 to 6 "C" or "D" batteries or equivalent. The bulb is $14.95 or something like that. I put one in my 4-"D" Mag Light, it works great.

Burton

Those bulbs aren't as powerful as some new LED emitters, but will be a big improvement over the original bulb and run much longer off a battery. Like that Lithium one you have in mind. I get 9 hrs runtime from a 5.6Ah Lipo RC battery and a 10W LED. You'd probably get 10x that.

fietsbob

Old 12v Nightrider 2 halogen bulb headlight's NiCad battery pack is 13.2v fully charged,[11x1.2v]
drop off to 12v does not take long..

Battery power source is drawn down by the load demand,
not pushed to the load like by a dynamo..

I ran my old 6v lights off a 5 D cell battery pack, just fine ..
1.2v x 5 =6v, if they were alkaline batteries rather than rechargeable, =7.5v.