znomit

I have the cyo premium on my training bike and the IQ-X on my randonneuring bike. The IQ-X is a nice upgrade. The dark line between nearfield and farfield isn't particularly annoying. My problems with it appearing to flicker went away when I swapped to the old style steel mount.

Harhir

Thanks. Yes I have a read several concerns about this cheap plastic mount and that it either loosens or even breaks. I do have a few old style steel mounts at home which I am planning to use one of them.

But its me 

I also experienced the plastic mount cracking. Upgraded to a Supernova LT310 mount. That's a solid, all metal mount that will last. Not sure why B&M cheated out on the mount for the IQ-X. That's it's only weakness, in my opinion. Never going back to battery lights.

unterhausen

I believe that they wanted an appearance upgrade with the IQ-X, and the mounts made out of steel rod just didn't do it for them. Going to a nice machined mount like Supenova was a step too far for the desired price point. I really am pretty happy with my IQ-X, been getting some quality night riding in, and it has been good.

znomit

150 lux 7.5w ebike version is out. Guess that means the Dynamo version is ~5W
https://www.elektrofahrrad24.de/busc...e-164r60ts7-01

fietsbob

E bike version would be running off the DC power source, the battery, where the hub dynamos are Alternators , putting out AC.

saturnsc2

all led's need direct current, but the ebike version needs more voltage than from a bicycle dynamo it seems....

Scummer

That is correct, because the Ebike runs at 12V and provides 12V connections for the headlight.
Hub Dynamo is 6V and has normally a rating of 3W. Far from the 7.5W this headlight needs.

znomit, the Dynamo provides 3W max, so you can't run more than a 2.4-2.6W front headlight, because the taillight also needs a bit of power. Mostly in the .4 to .6 range.

noglider 

My understanding is that a hub dynamo can produce a range of voltages depending on speed. Lights built for dynamos are designed with the assumption that the bike may not go faster than the speed that produces 6V even though it does at times. If you ride fast, you should be able to get 7.5W, but I don't know about the voltage curves of dynamos.

Scummer

It's not the power that goes up, since the type of generator limits the current to 500mA and under load for example 2.4W, the voltage goes up to up to 8V at high speeds. This is not good for LED lights, unless they have a voltage limiter built in like the Edelux light, which limits the voltage to 6.8V max. So the generator will produce a higher voltage, but only 6.8V and 500mA max will be at the LED bulb, making this a max of 3.4W.
If you would hook up two LED lights in parallel and therefore trying to draw a current of roughly 800mA, the voltage would break in so badly that probably none of the LED lights would light up.

steelbikeguy

The 7.5W value is very close to what I measured for my first generation Schmidt dynamo last year.

I set up a switchable resistive load for the dynamo and measured the voltage out of the dynamo at different speeds for each resistor value....



At 20mph (about the fastest that I'm going to be going on this bike), I measured 7.6 watts when the dynamo was connected to a 40 ohm load.

Many/most of the LED headlights do use a switching power supply to better match the LED to the dynamo. With a bit of extra engineering & parts, the light could optimize how much power is extracted from the dynamo at any speed, and could achieve the 7.6W that I measured with a 40 ohm load at 20mph.


Steve in Peoria

noglider 

What is a typical load of a modern LED headlight? How much power do you think you could expect from a hub dynamo at, say, 10 mph?

Scummer

Voltage = SQRT(Power x R) So SQRT(7.5x40) = 17.3V You would be way out of the operating range for an LED headlight, which should be no more than 6V when its dynamo driven. That's the reason why a Voltage regulator is build into the Edelux for example, in case you are not running a taillight from the headlight, which together would draw the normpower of 3W and limit the voltage at the dynamo to a little under 7V even at 20mph.
Without the taillight and no voltage regulator, the voltage on the LED bulb would go above 7V and shortening the life of the LED to a couple of days.
so, 6V at the maximum current of 500mA the dynamo provides, since the principle of the Dynamo limits the current, you can only extract 3W for the light, unless you run two lights in series, but having the problem of no light at low speeds, since you need the proper voltage to get the LED to power up.

saturnsc2

there are 12 volt 6 watt dynamos but still they come up short of the required current....

steelbikeguy

My post didn't mention any specific headlight, so clearly I'm not making any comment about the voltage ratings for the Edelux. The post was only intended to provide a data point for how much power can be drawn from a typical hub dynamo.

I can tell you that I've designed and built a few LED headlights for my own use, and have never used a voltage regulator to protect the LEDs from the dynamo voltage. The LEDs that I've used have been 3W versions and can handle 1A. They do a fine job of acting as a shunt regulator and clamping the dynamo voltage.

One of the lights I designed did automatically switch between running two LEDs in series and running 4 LEDs in series. The switching was based on the dynamo AC voltage frequency. Kinda crude, really, but did the job. This allowed it switch between roughly 300 lumens and 600 lumens (using Cree XR-E LEDs), drawing 3 or 6 watts, respectively. Surprisingly... there's not much visual difference between 300 and 600 lumens.


Steve in Peoria

steelbikeguy

with my test apparatus, I found that the max output power for my SON at 10mph was 3.6 watts, when presenting a 20 ohm load to the dynamo (with the caveat that my testing was limited and had the goal of getting "close enough"). With the "standard" 12 ohm load, the power is roughly 3 watts.

In the days of incandescent bulbs, the bulb was roughly 12 ohms when it was hot. With modern LED lights, I don't know if they try to stick with the 12 ohm standard or not. Since I make my own lights, I've never analyzed a production one.

...although... I did fix a fellow's Supernova Triple dynamo headlight this spring. Boy... it is a very curious design! It generally runs 3 LEDs in series, but also has a home-brewed buck converter to drive one LED at low speeds. I had fun reverse engineering it. Here's a photo of one side of the circuit board. The designer was nice enough to use common parts, making it possible to figure it all out...



It's a pricey light, but really well built.
I did a thread about the repair of this light on the candlepowerforums.....
repairing a Supernova Triple dynamo headlight

regarding the equivalent input resistance of LED lights... I wonder if znomit knows. He tinkers around with production lights more than I do, I believe.


Steve in Peoria

Scummer

Well.. my electronics courses have been 25 yrs ago, but I do remember, you need to protect a LED against current.
So, assume a cree XR-E from the data sheet has a forward current of 700mA, which looking at the diagram leads to a forward voltage of 3.5V.
In a very simple current protecting circuit, we would have to use a resistor of 2.5V/700mA = 3.5Ohms with a 2.5V*0.7A power rating, so 1.75W. That is rather a large resistor to dissipate so much heat, but I'm sure a switching power regulator will do a lot better than our simple resistance with LED circuit.

Basically a LED has Voltage where the semi conductor starts to switch from non conducting to conducting and would be causing a current overload on the LED if the voltage would actually be 6V directly connected to the LED.

So in conclusion, they are not sticking to the 12 Ohm standard, but to current limiting circuits to not destroy the LED with more current than the LED can take.

steelbikeguy

Fortunately, the dynamo itself performs that function. Recall that bicycle dynamos are specifically designed to have enough source impedance to intrinsically limit the current to roughly 0.5A or 0.6A.

If you use a current meter and measure the output of a dynamo, you'll be effectively shorting out the dynamo. You should see roughly this amount of current when you spin the dynamo.

In my tests on the first generation Schmidt, I measured the output voltage with a variety of load resistances, ranging from 1 ohm to 50 ohms (and made a few measurements with no load connected, just for the heck of it). I made these measurements at speeds from 5mph (8kph) to 20mph (32kph).
The most current that the dynamo produced during this testing was 0.63A.

If you build a dynamo LED light with just a full wave rectifier and one or two LEDs in series, then no current or voltage regulation is required.

As an example of this, the Supernova Triple light that I repaired did not use any sort of regulator for the LEDs in the headlight. The light did use a voltage regulator to feed its taillight, though.. which is one reason why you can only use a Supernova taillight with this headlight.

I do suspect that you are correct that manufacturers aren't using the 12 ohm standard for the headlights, though. I'd love to see some measurements on a variety of headlights to prove or disprove this, however.


Steve in Peoria

znomit

Check out Martins charts below. We went through all this 10 years ago when the bike light manufacturers were behind the curve. Yes you can pull more than 10W off a shimano dynamo if you string enough LEDs together. The drag becomes noticeable.

Dynamo LED Light Systems for Bicycles (electronic circuits)

The modern lights are so good there's a new generation of lower powered (1.5W instead of 3W, whatever that means) hubs coming out... I guess we might start hearing about compatibility issues with the bigger lights.
https://www.rosebikes.co.uk/article/...amo/aid:742795
https://www.rosebikes.com/article/sh...amo/aid:742159

DMVwheels

I am currently piecing together a new bike and I'm going the dynamo lighting route. I'll be mounting an IQ-X hanging from the side mount on my randonneuring rack and I am curious where the DRL sensor is located. In all likelihood the light will be under, or at least partially under, a randonneuring bag most of its life. Will this cause issue with the DRL sensor?


Also, can an M6 bolt fit through the ring mount? I wouldn't be using the stock mount and would directly bolt the light to the rack.

Emoncept

The Day/Night sensor is on the back under the silicone ring.