Portable charger for cyclists- Powers and charges small electronic items and is operated simply by p

[summerdays]

I would say that generally (apart from forgetting to charge my phone) I don't run out when normal day to day cycling. It is more of a problem when touring - I B&B'd so took chargers to use at night but I would see it as more of a problem if camping.

 

[PrettyboyTim]

As well as the humble dynamo, I have also been looking at more technologically advanced solutions which wouldn't have the same detrimental effect on cycling effort.

I'd be quite surprised if you could improve much on modern hub dynamos; as I understand they're very efficient already. If you need a lot of energy to charge something (like a laptop), it's got to come from the cyclist somehow and I'm guessing the best available technology for that is a hub dynamo.

I guess the area you might be able to make a difference would be something clever that did things like vary the load on the dynamo depending on the gradient of the surface the cyclist is riding on; uphill the battery wouldn't chrage at all whereas downhill you could take quite a bit of energy from the front wheel without it being unpleasant for the rider.

 

[very-near]

Lithium ion batteries offer such good storage nowadays, I struggle to see there being a decent demand for chargers like this. Anything which slows the rider down is not going to be welcome IMO

You could always invent a turbo trainer mod using an alternator (12v battery and inverter) to charge up lights, or alternatively a charger for a decent lighting system which stops drawing current when the chain is moving thus only slowing a bike on the freewheeling bit as said above.

 

[bonj2]

i wouldn't ever have any kind of dynamo, electricity-from-pedal-power type device on my bike purely because it would sap energy and cause me to slow down, like riding with the brake on, when this isn't necessary

 

[hackbike 666]

i wouldn't ever have any kind of dynamo, electricity-from-pedal-power type device on my bike purely because it would sap energy and cause me to slow down, like riding with the brake on, when this isn't necessary

I have for years on my commute.I suppose that's fine if you have some sort of ego and want to beat everyone who cycles.I know I do but it isn't working like that at the moment.It would actually be interesting to ride a light bike on my commute to actually see how fast I really was.

But as I said it's more important me getting there with the least amount of faffing about.My bike is for commuting not racing.

 

[garrilla]

I've seen a few sites where they show you how to build a frictionless magneto dynamo that can charge a light or ipod

here's one example
http://www.freelights.co.uk/

 

[palinurus]

i wouldn't ever have any kind of dynamo, electricity-from-pedal-power type device on my bike purely because it would sap energy and cause me to slow down, like riding with the brake on, when this isn't necessary

I've just started using a Shimano ultegra hub dynamo. In use it's barely noticeable, if I switch my light on while steadily pedalling on the flat I can't tell the difference. It is obvious if I spin the wheel by hand- it stops after a few revolutions when generating- so there is resistance there.

 

[bonj2]

I have for years on my commute.I suppose that's fine if you have some sort of ego and want to beat everyone who cycles.I know I do but it isn't working like that at the moment.It would actually be interesting to ride a light bike on my commute to actually see how fast I really was.

But as I said it's more important me getting there with the least amount of faffing about.My bike is for commuting not racing.

with all due respect, you work and live in the same city.
how long's your commute?

 

[bonj2]

I've just started using a Shimano ultegra hub dynamo. In use it's barely noticeable, if I switch my light on while steadily pedalling on the flat I can't tell the difference. It is obvious if I spin the wheel by hand- it stops after a few revolutions when generating- so there is resistance there.

if it's hardly noticeable it's not generating enough light. Probably doesn't generate enough to actually see by on dark country lanes, rather than just be seen, does it? Otherwise you may as well just use a smart 5-LED, the batteries will be lighter than the dynamo workings probably. But if you like it, fine - i'm just saying i wouldn't use it.

 

[hackbike 666]

with all due respect, you work and live in the same city.
how long's your commute?

Errr ten miles.

 

[palinurus]

if it's hardly noticeable it's not generating enough light. Probably doesn't generate enough to actually see by on dark country lanes, rather than just be seen, does it? Otherwise you may as well just use a smart 5-LED, the batteries will be lighter than the dynamo workings probably. But if you like it, fine - i'm just saying i wouldn't use it.

I've got a B&M Cyo. It really is pretty bright. I bought it so I could ride on unlit roads without having to consider run times/charging etc.

 

[Dr Tiernan]

Reply to thread

Thanks again for the replies everyone.

I'd like to get a better idea of what sort of cyclist uses a dynamo. It seems like the more likely market for a dynamo would be touring, holidaying cyclists or commuters who are not overly fussed about a little extra weight; as opposed to racing cyclists who pay a premium to save on weight and wouldn't want the extra drag.

i wouldn't ever have any kind of dynamo, electricity-from-pedal-power type device on my bike purely because it would sap energy and cause me to slow down, like riding with the brake on, when this isn't necessary

What sort of cyclist are you bonj?

Does anyone think there is a market for a dynamo that 'knows' when it's going uphill and so disengages itself?

Modern hub dynamos appear to give minimal drag, palinurus says "In use it's barely noticeable, if I switch my light on while steadily pedaling on the flat I can't tell the difference." Does anybody else have any experience with hub dynamos? Good/ bad?

 

[PrettyboyTim]

if it's hardly noticeable it's not generating enough light.

But what at what percentage of effort does it stop becoming noticeable? 1%? 5%? 10%

Let's say someone is cycling along, not particularly hard, and generating 150W of power. Let's assume 95% of that gets to the bike - 142W. Now let's say that the dynamo uses up 5% of that power - 7.1W, and let's say the dynamo is 85% efficient - 6W.

A Cree LED can generate 130 Lumens/Watt (I think some can do 200 Lumens/Watt now) so you could get up to 780 Lumens from that 6 Watts.

780 Lumens is a lot of light, considerably more than most bike lighting systems. I'm not sure how many Lumens you feel you need for riding in the dark; I guess it depends how fast you want to go.

My guess is that I'd be quite happy riding in the proper dark with a decent 3W light, which would take 2.5% or less of the power I was putting in to the bike.

 

[Twenty Inch]

Thanks again for the replies everyone.

I'd like to get a better idea of what sort of cyclist uses a dynamo. It seems like the more likely market for a dynamo would be touring, holidaying cyclists or commuters who are not overly fussed about a little extra weight; as opposed to racing cyclists who pay a premium to save on weight and wouldn't want the extra drag.

Exactly

What sort of cyclist are you bonj?

Don't ask! Bonj is the resident technical expert, who can demonstrate that farms are useless, and that horse-riding isn't exercise.

Does anyone think there is a market for a dynamo that 'knows' when it's going uphill and so disengages itself?

Modern hub dynamos appear to give minimal drag, palinurus says "In use it's barely noticeable, if I switch my light on while steadily pedaling on the flat I can't tell the difference." Does anybody else have any experience with hub dynamos? Good/ bad?

I think that your best bet is not to "invent" a dynamo, but rather to look at developing the bit that sits between the dynamo and the appliance. I'm a busy cyclist with a hub dynamo who can see the value of being able to charge things off my pedalling effort, but I'm not going to buy something else to go on the bike. Design a junction box that can be inserted between the dynamo and the lights, and that lets the user select whether to charge a phone, a couple of AA batteries, a laptop, a GPS, or run his lights, and you may have a winner. Make it waterproof, robust, and easy to use, and you'll crack the touring market.

 

[hackbike 666]

Or you could go the whole hog and invent time travel.