RichinSC1

Anyone have experience using a bike dynamo for charging cell phone, lights, etc? I saw someone used some capacitors to make it cell phone/DC compatible. If it works it sure would be a cheap and easy way to charge things while on a ride.

steelbikeguy

Sinewave makes a reliable device for this purpose. https://www.sinewavecycles.com/

There are other sources for this sort of thing too.

There's no reason a person couldn't cobble together a reasonable version of this too. The basics would include a bridge rectifier, filter caps, and a 7805 5V linear regulator. Of course, when the battery is fully charged, the dynamo voltage will rise quite a bit, and some sort of voltage clamp will be needed to protect the 7805.

Steve in Peoria

gsa103

$120, yike.
You could probably cobble something together with a rectifier, some caps and a buck converter.
A 7805 is very good a providing at reliable supply, but they're not at all efficient. Any excess voltage simply goes into heating the regulator.

You can buy buck converters for about $5 or you can get custom circuit boards fabricated for about $20 (for 10 boards including shipping), so you can affordably do a full custom if you want.
I've given up even bothering with proto boards anymore. I do a basic test of critical things on a breadboard then straight to a custom PCB. There's usually a mistake somewhere, so it costs me a little more, but the final product is better.

Tourist in MSN

These are quieter and a bit more trouble free.



That is simply an alternator, you still need the USB charger like steelbikeguy mentioned.

Or you can directly power lights from it without the extra electronics.

unterhausen

A sidewall dyno is very inefficient and the chargers cost a lot. I have dynohubs on all of my bikes and I just carry battery packs to charge things with. They don't weigh much for a very large capacity.

PaulRivers

They sell everything you'd need to do it but it's expensive. Apparently the issue is that dynamo's produce alternating current, while charging uses direct current. Also charging often handles constantly varying degrees of out put poorly (like how it produces a lot more electricity going diwnhill that it dies uphill).

If your bike touring and throw some cash at it it can definitely be done. But it's not cheap for the casual user much easier to charge at home or even bring an extetnal battery that you charge at home if needed.

noglider 

Battery packs are a better solution for almost all cases. Four of them weigh less than a dynamo hub. A bottle dynamo makes a lot of drag for a little amount of power. The charging circuitry is expensive. I think it makes sense to use a dynamo for charging ONLY if you're going to be away from a power outlet for several days.

I use a dynamo hub to power my headlight day and night. I find it to be cost and trouble and drag justified. I use battery packs for charging my phone, and I could use it to charge my taillight etc.

unterhausen

I think that those usb chargers probably work better if they are charging a battery anyway. Last I looked, Anker still made batteries with pass-through charging. My only experience with USB chargers was a Luxos U headlight, which might not be the best example. But the first time I used it to charge my GPS, it was infuriating. The route featured 50 miles of gradual uphill, so the charger was continually dropping out and a Garmin 800 is programmed to beep and put up a message every time that happens.

Tourist in MSN

Luxos U has a tiny little pass through cache battery. And if you are riding slow (typically uphill), more power can come out of that internal battery than your hub is producing, which depletes the internal battery. When the battery is depleted, It then stops sending power to the USB port (your Garmin will let you know when this happens), and for several minutes it will charge up that internal battery, and then it will again send power to the USB, but if you are still riding slow, then it won't be long before it stops sending power to the USB again (and your Garmin lets you know that again), and you get frustrated.

In this case it is best to unplug your Garmin from the USB for at least a half hour, probably a bit more, that gives your internal battery time to charge up again.

But if you did that on the night portion of a brevet when your lights have to be on, no system will send much power out of the USB when your lights are on, your lights take most of the power.

My rando bike has a B&M IQ-XS and a Secula taillight, a Sinewave Revolution is also wired in parallel from the hub. On an exercise ride, I averaged about 2.5 watts out of the Sinewave (only measured when rolling) with lights off, but with the lights on I averaged only 0.6 watts out of the Sinewave. I was surprised that I got that much out of the Sinewave with the lights on, I expected zip. But still only a quarter of the power out of the Sinewave when the lights are on is not a lot of power, probably best to assume zero when planning. For planning purposes, I assume 2 watts out of the Sinewave with lights off.

When touring, I use the Sinewave to charge my my larger battery pack that is in my handlebar bag. That battery will work in pass through mode. It is a large battery, 44 watt hours capacity. I draw power out of that battery to charge my GPS when I get only two out of four bars on the battery. Hills do not matter in that scenario because the battery pack has a lot of capacity and won't run down like the tiny battery in the Luxos U.

I bought the Sinewave for touring, but when not touring, instead of putting the Sinewave in storage I put it on my rando bike. I mention this only because I suspect you are curious why I would install a Sinewave on a rando bike.

Some people that use a dynohub when touring use it to charge up a powerbank, and in the campsite they then charge up their devices out of the battery pack. In that case they do not use pass through capacity at all. But I prefer pass through so I can charge my GPS while rolling.

fourfa

Okay, I know the OP is about the old school bottle dynamos, and it immediately turned into a "vs dynohub" thread as expected. But there's also this:

VELOGICAL RIM-DYNAMO - Standard Bicycle Dynamo - Smooth Running, Lightweight, Efficient

New school high efficiency sidewall-powered bottle dynamo. More expensive than the old school to be sure, but still probably cheaper than lacing up a new wheel for most people, and arguably simpler

That said, I have dyno hubs available for all my bikes and there are still days where I grab a non-dyno front wheel and have a battery pack squirreled away if I think I'll need it. If cost is really an issue, battery bank is really where the bang for the buck is.

unterhausen

Something wrong with your link. google gives me this one VELOGICAL RIM-DYNAMO - Standard Bicycle Dynamo - Smooth Running, Lightweight, Efficient

The PedalCell is interesting https://www.cyclingabout.com/rim-dyn...n-hub-dynamos/

billridesbikes

A USB charger from a bicycle dynamo is easy to build and only needs a few cheap and simple to obtain components. I would not charge a device directly, but charge a battery bank and use the battery back to charge devices.

Here is one such circuit, but you can find several variations on the web.
Dynamo usb charger

steelbikeguy

the Velogical has been around for... maybe 8 years or longer?
The innovation was primarily that it was a bottle dynamo that didn't have the inefficiency of the roller that rubs on the tire or rim. The dynamo itself, i.e. the design of the windings, magnets, etc., weren't shown to be any more efficient than hub dynamos or other modern designs.
The power output was relatively low too, so it's not something that would be used to charge a battery even if you were to crack it open and find a place to attach wires.
Definitely a very clever design, though!

Steve in Peoria

unterhausen

Velogical has a version with a lot more power for charging at slow speeds. I gave this link in my previous post https://www.cyclingabout.com/rim-dyn...n-hub-dynamos/

I have to say that I generally prefer just enough power out of my dyno to power my lights. Although it is tempting to put a Velogical on a bike.

steelbikeguy

oops....
I was thinking of the Magnic light and not the Velogical. Sorry!

Steve in Peoria

Germany_chris

I just ordered a velogical for my commuter I also have a B&M USB-werk that I’ll probably pull off the touring bike and transplant. I’ll let everyone know how it all works out

gilesa

One thing to consider is that sidewall/rim dynamos run at about 10 times the frequency of hubs. So there may be a compatibility problem with chargers made for hubs, almost certainly so if they include boost/tuning capacitors like the Forumslader.

Germany_chris

Their site has what’s compatible

Germany_chris

The dynamo showed up today there are a few more thing that need to get here before I can install it