Charging my bicycle's lighting system (6V)

RandomJoe Solar Expert Posts: 472 ✭✭✭
Does anyone know if 6V charge controllers are available? I checked NAWS' site, but didn't see any...

Been tinkering with the 6V SLA for my bicycle lighting system, and a couple of small panels I got with 6V motion lights. Works, and would probably be fine without a controller since the panels are so anemic, but it would take 3-4 days to recharge after a single 1 hour ride! (Light is 10W so I use about 2AH in a ride, panels are about 100mA in full sun.) My HF panels could do the job handily, but of course would need a controller of some sort.

That does bring up another potential issue, a 6V PWM controller might not be designed to handle a high enough PV voltage for the HF panels - they'll go to about 25V OC...

I might just cobble something together myself, for the fun of it, but was curious if there are 6V PWM controllers around...


  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Charging my bicycle's lighting system (6V)

    Whatever happened to generator lights? Don't they make them anymore? Used to rub against the back wheel and put out an anemic 6V AC. I remember adding a rectifier & capacitor to stabilize the Voltage because the lights would go dim when you slowed and brighten when you sped up!

    Back when I could still ride a bicycle. Fancy one; had three speeds in the hub. :D

    I think you'd have to build your own Voltage regulator system to charge 6V batteries, or lift and adapt the circuit from a 6/12 auto charger. Fortunately you're not dealing with a lot of current here so there's plenty of margin!
  • RandomJoe
    RandomJoe Solar Expert Posts: 472 ✭✭✭
    Re: Charging my bicycle's lighting system (6V)

    I think they still make those generator sets. I'm not about to have something rubbing against the side of my expensive skinny tires though! :p I never liked the light going out when I stopped anyway, so have to add a battery too...

    What they do have, that interests me some, is a hub generator. I could replace the hub of my front wheel with this generator and make quite a bit more (and more reliable) power.

    This current light set is pretty old - bought it back around 2001. Uses a 10W halogen bulb, and as mentioned lead-acid batteries. I could buy a new set that uses LEDs (some just as bright) and a skinny LiPo pack, and be down to a fraction of the weight. But well... This one works, so why spend the money? :D

    One thought I"ve had, is to take a closer look at the AC charger that came with the kit. The actual charging circuit is in a plastic case on the cord, the wall-wart is a typical 9V 500mA wall-wart. Be nice if I could just use that charger circuit, but I'm not optimistic that it will like having 20-25V on its input when finished charging! Have to look, I might get lucky...

    Oh, my bike isn't just fancy, it's overboard! :cool: I ride a recumbent, and added a 3-speed rear hub to the 3 chainrings and 9-speed cassette. I have 81 gear selections to choose from, it's almost like having a continuously variable transmission!
  • BB.
    BB. Super Moderators, Administrators Posts: 33,500 admin
    Re: Charging my bicycle's lighting system (6V)

    The old side of the wheel alternators really took a lot of peddling power (at least for a 12 year old--sidewall dynamos are not very efficient)...

    Gee--this looks exactly like the one I had for my bike 4+ decades ago...:roll:

    I really like the LED (or even HID) lights out there and reasonable weight battery packs. Add that even NiMH are 2+x the power storage per cell vs the old NiCAD's--I would think that the side of the wheel alternators are pretty much end of life... But I don't get to ride a bike much anymore (not that I was ever that much into them $$$$). :cry:

    And who-new? The subject of bike dynamos can be controversial. :roll::roll: Links to nice dynamo systems in above link (this link may not be quite safe for work).

    Anyway, here is the link to the general Bicycle Lighting site:

    Regarding a regulator for solar panels (or even dynamo)--You may not even need one if the output current is less than 10% of the battery AH capacity... And if you are going to be riding long distances--you would be better off lifting the dynamo or turning off the dynamo to reduce drag once the battery bank is charged anyway.

    Down converting from a dynamo to battery pack--MPPT type function--probably not practical at these low power levels for somebody to design and market...

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset