Originally Posted by
mrbubbles
Maybe you're not understanding it correctly. That's also entirely possible.
Possible, but considering your claims (which are based upon your subjective perceptions instead of objective measurements) require power output from a dynamo that is far in excess of what any reputable source has ever claimed it is much more likely that you are the one mistaken.
Originally Posted by
mrbubbles
I would think reputable manufacturers like Supernova/Exposure knows what they're doing, if they claim 800 lumens out of 3/4 leds (which would require 8w+) and it only puts out 5w equivalent of light, that's serious false advertisement (that's what you're accusing them of). I suspect their lights put out maybe 700 or so lumens instead their claim of "800", but that still shows the dynamo can power the leds beyond 5w.
So, you admit that those reputable manufacturers are 'fudging' their claims (since they have never actually measured their devices) but you just want to believe they are only fudging a little bit. However, I did notice that you haven't actually provided any engineers statement (as opposed to the marketing guys) who claim their lights are receiving more than 4-5w...
Originally Posted by
mrbubbles
Only in your mind. You haven't been on this forum long enough. I have 3 dynamo DIY front lights (2 of them are posted). Every post on this forum made by a member is logged so when you can go back to my entire posting history and it will show that I've only posted 2 dynamo front lights.
First, I wasn't talking about head lights there, but tail lights. You have shown more than 3 versions of such...
Originally Posted by
mrbubbles
My claims are well below the estimate of the spec sheets (which are reasonable benchmarks to go on and as usual you are more than welcome to disagree).
The spec sheet for the Cree XR-e shows a 100 lumen per watt curve.... Your claim of 1000 lumens therefore requires at least 10 watts from the dyno, actually quite a bit more considering how inefficient your circuit is in providing power to the LED. Actually, given the inefficiency of your circuit, even the revised 600-700 lumen claim would require nearly 10 watts from the dyno.
And dyno's are designed to produce their maximum power output with a 12 ohm load. And as I have provided actual objective evidence, the maximum power any current bicycle dyno can produce is in the 4-5W range.
And while I agree spec sheets are reasonable to go on in estimating lumen output from a led, using them requires a much better understanding of the actual environment than you have provided any indication that you possess. One thing is in no doubt, you have no idea how much power your delivering to your particular LED's, nor do you have any objective information on how much light they are producing...