2015 - latest hotness in cutoff battery lights?

[Savvas]

There are plenty of accounts all over the net - mainly from the audax crowd - that give experience-based Cyo+battery advice. Here's one PBP experience: http://mccraw.co.uk/battery-powered-dynamo-lighting/ My main concern would be that the Cyo has an effective current regulator inside - it sounds as though this is the case!

Savvas.

 

[Marcturus]

Go ahead, feed your CYOs 47V DC then. Not what YOU were saying, Savvas, I know.
(And here my interest in reruns of cyo voltage discussions ends.)

 

[woahdae]

No, not DC, trying out will actually fry most CYOs very quickly.

Thanks! Maybe saved me a CYO. Someone advised that the "T" models can be run off an E-Bike battery, and other models off a smaller battery.

I asked about it somewhere else and got crickets. Maybe this is an application of Cunningham's Law: "The best way to get the right answer on the Internet is not to ask a question, it's to post the wrong answer."

 

[woahdae]

Go ahead, feed your CYOs 47V DC then. Not what YOU were saying, I know.
(And here my interest in reruns of cyo voltage discussions ends.)

Ok, well, tossing a grenade in and running away... especially after asking for citations and accusing me of posting nonsense for fake internet points.

I managed to find the CYO manual, and it says it can be run at 7.5v DC: http://www.starbike.com/images/BUMM/PDF/175q.pdf. Not the 48v rating I had found earlier, but it's hard to find and re-find dynamo light specs. Maybe I was reading a "T" version by mistake.

And some guys on another forum found that the 7.5v warning is a bit conservative, running it as much as 10v to achieve full power: https://yacf.co.uk/forum/index.php?topic=43791.25

The manual of the Luxos non-T version does explicitly state it cannot be run off dynamo power.

If you don't want to get blamed for giving awful advice, try making harmless contributions to boost your post count. Or at least provide a link to your source and carefully qualify the exact Cyo models you are writing about

Likewise!

 

[Savvas]

I think the main thing to consider in pursuing a dynamo light/battery power combination is how battery LED supply works differently to generator LED supply. I understand - at a very basic level - that current regulation in the case of dynamo supply is taken care of by the generator itself and voltage is simply a function of how many LEDs are arranged in what pattern. Battery supply works quite differently and without current regulation of some sort in the circuit a battery can easily dump all of its current into the LED with fatal results. Hence my previous reference to need for both current regulation and attention to battery tolerances if wanting to use a battery supply with dynamo lights.

I guess the 'complication' is that lights such as the Cyo are not simple LED circuits - they have both a bridge regulator [Edit: I meant to say 'bridge rectifier' of course] and other more complex circuitry inside - I presume aimed at optimising both current and voltage supply to the LED(s) as much as possible. The dynamo lights internal bridge regulator would - I assume - ensure that the battery supply would work OK whichever way it was connected. And the experiences documented in the link I provided about the Cyo's use for PBP suggests that whatever regulation there is inside is able to cope with at least low battery voltages From memory I think a supply of DC 7.2V appears to work fine and I think the author also indicated that up to 9.5V works ok too (but please read the article - I'm relying only on memory!) Mind you I most definitely would not assume that any dynamo LED light could tolerate battery voltages higher than this without using some sort of DC-DC converter simply because that's not what they are built for!

I have a passing interest in electric bikes and trikes and a couple of years ago did a search for 'cut off' electric bike lights. I found that both Philips and B&M made them and also I think other European companies such as Trelock and Axa. I got one of the Philips e-bike lights from Bike24 (an 'EF' designation I think) and the only physical difference I can see between it and the dynamo version is the lack of a switch on the e-bike model. It will tolerate 6-48V but as I've said, it's specifically made for e-bike use! Incidentally, from a few obscure references and pictures on Aliexpress, it appears that China is busily producing e-bike clones of the B&M!

Savvas.

 

[Steve K]

on the subject of dynamo lights and the design of their power conditioning circuitry.... I'm waiting for someone (or many people) to reverse engineer some of them and see how they work.

In the days of incandescent bulbs, we all knew that the bulb was roughly 12 ohms and was happy with AC or DC.

With LEDs, there needs to be some sort of converter circuit in order to deliver 3 watts to a single LED when the LED has a forward voltage of 3V. It's probably a buck converter, but who knows what variables might exist.

Assuming that it is a buck converter, then it will be designed to operate over some range of voltages. Connected to a typical dynamo, it shouldn't see voltages much above 7 or 8 volts, so I wouldn't expect them to be designed to withstand more than 10 or 15 volts.

My advice would be to be careful if using lights in a way that the manufacturer didn't plan on. And if you do kill the light, consider sending me the light's remains.... I'm still looking for a good dead light to throw my own circuits into.

p.s. nice to see Sam on the list again! heck.. it's nice just to see some activity on the list again!