Alternative Power sources - Re: Bicycle Lighting System?

Author

Re: Bicycle Lighting System?

Martin Riddle

2008-03-01, 5:25 pm

I use one of those flashing LED rear lamps.

And a converted head lamp with a 6v Kryton bulb driven off 4 1200mAh AA's. Its 2hrs of light.

You could use this araingment and use your Hub generator and a Bridge tied to the batteries. Not a problem for short trips or
a casual rider, but extended trips and high speeds may over charge the batteries.

Also, be sure your hub is isolated. Other wise if one end of the hub winding is tied to GND then a single diode should be
used instead of the bridge.

4W at 6V is 0.666 A a 1A rectifier is best,

HUB---------|
|
/A\
/ \
GND _____/- +\___________________Lamp
\ / |
\ / | GND---Lamp
\A/ +B
| A
HUB---------| T
-
|
GND
Cheers

"(PeteCresswell)" <x@y.Invalid> wrote in message news:c5ijs39mg1hg6flkr4upf6ioev26g267jm@4ax.com...
> Posted here bco the obvious expertise of group members in matters
> electrical.
>
> Bicycle-mounted front wheel generator (alternator?) hub - puts
> out AC.
>
> Numbers on the hub say 6 volts, 4 watts.
>
> Putting a volt meter on it, I get 3v at walking speed (2.5 mph),
> 6v at 5 mph, and more as speed increases. With me on it, I
> don't see it ever getting up to 20v, but 10-12v could be fairly
> common.
>
> From what I've heard, there is a problem with using bulbs wired
> direct. You get a bulb that won't burn out at the higher
> voltages, and it's dim where most of the riding happens - at 5-10
> mph. It also goes out when the bike goes really slow or stops.
>
> I'm basically clueless re/electrical stuff, but what I've gleaned
> so far is this:
> ------------------------------------------------------------------
> 1) Something called a bridge rectifier will convert AC to DC.
>
> 2) If I put a couple of 1.5v NiCad batteries end-to-end, but
> across the rectifier's output, they'll be charged when the
> output exceeds 3 volts and supply 3 volts when the output is
> less than 3 volts - limiting the voltage that any bulb or
> LED emitter is subjected to about 3 volts.
>
> 3) There are myriad 3-volt LED lights out there that I can choose
> from for the lighting part. Red, white, steady, flashing....
> you name it, somebody's selling it.
> ------------------------------------------------------------------
>
> Bottom line, I want maximum brightness when just noodling along
> at 3-7 mph, but don't want tb burning out bulbs if/when I go down
> a hill fast.
>
> My primary concern is the lighting that's visible to closing
> traffic from my back. I avoid roads with any significant amounts
> of traffic, but even in the quietest neighborhoods and parking
> lots there's some exposure.
>
> The more light and the more attention-getting on the rear the
> better, since I'm competing with cell phones, text messages,
> email, and navigation screens.
>
> I use a hand-held flashlight for the front lighting and it works
> well. (Lowe's TaskForce 4w LED... one *brave* little flashlight)
> .. but I also want a token front light attached to the bike and
> wired into the system in case some cop wants to get technical or
> the hand-held fails when I still have to get back to my home.
>
> Am I on the right track? Seems like the capacity of the
> rectifier would be a half amp max (4w/20v + fudge factor).
>
> One more time: I'm clueless about electrical stuff.
> --
> PeteCresswell

(PeteCresswell)

2008-03-01, 5:25 pm

Per Martin Riddle:
>
>
>HUB---------|
> |
> /A\
> / \
>GND _____/- +\___________________Lamp
> \ / |
> \ / | GND---Lamp
> \A/ +B
> | A
>HUB---------| T
> -
> |
> GND

That was *quick*... I'm not even seeing my OP yet.

Is the diagram above predicated on an "isolated" hub?
--
PeteCresswell

Martin Riddle

2008-03-01, 5:25 pm

"(PeteCresswell)" <x@y.Invalid> wrote in message news:cnljs39sd92jgs7dts2nsbs2g4hmurr0ca@4ax.com...
> Per Martin Riddle:
>
> That was *quick*... I'm not even seeing my OP yet.
>
> Is the diagram above predicated on an "isolated" hub?
> --
> PeteCresswell

Yes!

(PeteCresswell)

2008-03-01, 5:25 pm

Per Martin Riddle:
>I use one of those flashing LED rear lamps.
>
>And a converted head lamp with a 6v Kryton bulb driven off 4 1200mAh AA's. Its 2hrs of light.

There's not doubt whatsoever in my mind that the rational
solution is battery-powered lights. They're everywhere - and on
sale right now at Performance. Witness my own hand-held
flashlight (2 C batteries - probably be putting out light on the
original batts long after I'm dead...)

But now I've got this Sturmey-Archer Dynohub (was planning on
just a drum brake... but the drum + generator was only five bucks
more...) so, just for grins, I'd like to make a system that works
without batteries.
--
PeteCresswell

Gordon Richmond

2008-03-02, 9:25 am

>Per Martin Riddle:
>
>There's not doubt whatsoever in my mind that the rational
>solution is battery-powered lights. They're everywhere - and on
>sale right now at Performance. Witness my own hand-held
>flashlight (2 C batteries - probably be putting out light on the
>original batts long after I'm dead...)
>
>But now I've got this Sturmey-Archer Dynohub (was planning on
>just a drum brake... but the drum + generator was only five bucks
>more...) so, just for grins, I'd like to make a system that works
>without batteries.

I think you could make it work. Even if the dynohub is grounded, you could use a bridge
rectifier; just ensure that anything on the DC side is NOT grounded.

I'd set it up as a six-volt system. That's what it's rated at. Running 3 volts
lamps/batteries, there's too much likelihood of overcharging batteries or burning out
lamps. You could run some pretty impressive LED lamps with 4 watts of power.

Set it up with a plastic battery-holder and 4 AA cells. Try nicads or alkalines. The
latter aren't supposed to be rechargeable, but likely a SMALL reverse current won't kill
them. The bridge rectifier should keep the batteries from backfeeding the alternator coil.

Sounds like a fun project. Good luck with it.

Gordon Richmond

clare at snyder.on.ca

2008-03-02, 5:25 pm

On Sun, 02 Mar 2008 13:16:41 GMT, Gordon Richmond
<richmond@telusplanet.net> wrote:

>
>I think you could make it work. Even if the dynohub is grounded, you could use a bridge
>rectifier; just ensure that anything on the DC side is NOT grounded.
>
>I'd set it up as a six-volt system. That's what it's rated at. Running 3 volts
>lamps/batteries, there's too much likelihood of overcharging batteries or burning out
>lamps. You could run some pretty impressive LED lamps with 4 watts of power.
>
>Set it up with a plastic battery-holder and 4 AA cells. Try nicads or alkalines. The
>latter aren't supposed to be rechargeable, but likely a SMALL reverse current won't kill
>them. The bridge rectifier should keep the batteries from backfeeding the alternator coil.
>
>Sounds like a fun project. Good luck with it.
>
>Gordon Richmond
Never seen a grounded SA Dynohub. Not saying they don't exist, but
every one I've seen has been a 2 terminal isolated single phase AC.

--
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