Talk To Me About Dynamos

Rik · *by **Rik** on Fri 5/Feb/16 1:29pm*

I like to burn a lot of Kjs commuting each week/year. And my children burn a hell of a lot of my electricity charging various 'must-have devices' each week/year.

So I'm thinking, there must be a way to cancel out (or a least move the balance of) the two sides of this energy equation.

So what do you knowledgeable folk know about dynamo hubs?

adikt · *by **adikt** on Fri 5/Feb/16 1:41pm*

I recall my Mum talking about having one on her bike when she was a girl before they kind of went out of fashion.

I assume the tech has been slightly upgraded since then?

jo · *by jo on Fri 5/Feb/16 1:46pm*

I think the bikepackers have some funky ones running through their headtubes up to a USB port.

If you're interested in bike blinkies, I use and recommend these https://www.reelight.com/en/products/sl ... mpact-set/
Still running the same set on my commutter since 2009....

Rik · *by **Rik** on Fri 5/Feb/16 2:03pm*

adikt wrote:I assume the tech has been slightly upgraded since then?

just a bit.

swtchbckr · *by **swtchbckr** on Fri 5/Feb/16 2:11pm*

Ollie has the shiz... somewhere in his blog you'll find all sorts of info about his set up. it's mint
http://mountainpedalernz.blogspot.co.nz/
in fact, that first post http://mountainpedalernz.blogspot.co.nz ... ctory.html
says it all...

znomit · *by **znomit** on Fri 5/Feb/16 2:30pm*

The Shimano 3n80 hub is the one to get. For charging solutions either get the B&M Luxos light which has a USB port, or see the various gadgets at klite...
http://www.klite.com.au/#!products/c3oe

Rik · *by **Rik** on Sat 6/Feb/16 11:13am*

So these shimano hubs? Do they require a regulator recitifiers?

philstar · *by **philstar** on Sun 7/Feb/16 5:04am*

Rik wrote:I like to burn a lot of Kjs commuting each week/year. And my children burn a hell of a lot of my electricity charging various 'must-have devices' each week/year.

you will burn more Kjs with a Dynamo hub, unless you have massive amounts of down hill that you only turn it on for.

also

it is hard to generate significant amounts of power

Rik · *by **Rik** on Sun 7/Feb/16 1:00pm*

philstar wrote:you will burn more Kjs with a Dynamo hub,

Meh, I think I could handle loosing the 5-10watts it'd take to charge a tablet.

philstar · *by **philstar** on Sun 7/Feb/16 1:37pm*

Rik wrote:
philstar wrote:you will burn more Kjs with a Dynamo hub,

Meh, I think I could handle loosing the 5-10watts it'd take to charge a tablet.

10w (more like 3 though PV-8 Dynamo ) , 5V (usb voltage )= 2 amp tablet battery 5600mAh (5.6 Ah) = 2 (more like 6 ) hours of charging (assuming 100% efficiency).

at $120 for a hub and 30c (guess) per kWh, that is 400 kWh to pay for the hub, at 4 watts that is 100000 hours of riding just to recoup the cost of the hub in electricity.

now a generating stationary trainer you might be able to 100-200 Watts out of, which take it down to 2000 hours (but it would probably cost more like $480 which puts it up to 8000 hours, or 11 months 100% of the time)

so don't do it to save power,

Kev · *by **Kev** on Sun 7/Feb/16 4:45pm*

Don't you be bringing "facts" and numbers to this discussion.

swtchbckr · *by **swtchbckr** on Sun 7/Feb/16 9:54pm*

Yeah, it's not about the pay back time for the electricity you're saving! It's about generating the power yourself, right? Forget economics. Economists seem to think that perpetual growth in a finite system with finite resources is the possible, or indeed, the norm. How deluded is that? If you wanna charge your shit from your own work, then go for it.

I've heard the dynamos only 'drag' when they're taking power... ie, when you're not charging anything, they're basically neutral bearings. And when they are charging something or powering a light, the 'drag' is minimal. I've seen front wheels spun and continue spinning for a good while while charging, only slowing marginally faster than a non dynamo hub...

Hey, wouldn't it be good if we could get regenerative braking on bikes? No 'draggy' hubs and everytime we slow down we're charging shit up! :alien:

philstar · *by **philstar** on Mon 8/Feb/16 12:07am*

swtchbckr wrote:Yeah, it's not about the pay back time for the electricity you're saving! It's about generating the power yourself, right? Forget economics. Economists seem to think that perpetual growth in a finite system with finite resources is the possible, or indeed, the norm. How deluded is that? If you wanna charge your shit from your own work, then go for it.

I didn't say "don't do it" but just don't do it thinking you are saving power in any way (probably more electricity will be used in making the hub then it will ever generate). the best option would be to to not buy 1440000kJ of food (about 1/2 year RDI) (and that assumes 100% conversion of food to bike power).

swtchbckr wrote:Hey, wouldn't it be good if we could get regenerative braking on bikes? No 'draggy' hubs and everytime we slow down we're charging shit up!

totes, i was think old school tyer dynamos attached to the brakes so the activate first, but if you pull a bit harder/further the brakes come on.