USB/5Vdc Front&Rear Lights

[ConRAD]

Just investigating to totally rearrange my basic electrical bicycle system.
Considered that my most common use of bicycle is mainly travelling and day light commuting, that I need lights only occasionally in proximity of sudden tunnels or for a very limited time during dusk/dawn, well at this point I might finally give up to my beloved dynamo+converter+battery and use instead a couple of modern 20000mAh USB-C power packs to be eventually quickly recharged in turn at the first occasion.
I don’t want rechargeable USB lights but rather directly powered USB/5Vdc lights.
Any idea of any USB/5Vdc good quality lights?

[Tigerbiten]

As you want to run them off a single battery why not just use a 5v->6v DC/DC converter and dynamo lights.
The converter will run at ~99% efficiency and good dynamo lights are easy to find.
Or better still.
Why not check how bright dynamo lights are at 5v before doing anything else.

Luck .........

[ConRAD]

... and dynamo lights ...

Dynamo lights are basically conceived and designed to work with AC.
They definitely can work with DC either ... but this is NOT a good solution because in such a case only half of the 4-diodes bridge of the light would work, that causing useless overheating and efficiency loss.

[[XAP]Bob]

Depends on the lamp - some are certified for DC use, and some will relish up to 9v...

[ConRAD]

... some will relish up to 9v...

Indeed for testing purposes only I've already been checking for short whiles common AC dynamo lights with a 9V battery ... but what I'm looking for are nominal 5Vdc front and rear lights with no battery incorporated, perhaps anything like that?

[rjb]

In a previous post on the Aldi lights I asked whether it would be possible to run their usb charged lights from a usb power pack. The answer was affirmative. So this is a possible solution. I was considering using a simple bridge rectifier to run these lights from a dynamo but needed to know wether you could use a power bank as a 1/2 way solution.
viewtopic.php?t=141234&start=15

[ConRAD]

... I was considering using a simple bridge rectifier to run these lights from a dynamo ...

... sorry but a simple bridge alone doesn't make a 5Vdc stabilized output voltage !!!

[thelawnet]

There are hundreds of sellers selling such lights on Aliexpress

This is your best place to look, though for delivery time once you have settled on a light you might prefer to buy from Amazon or Ebay

E.g.

US $11.71 38%OFF | Waterproof 3XT6 LED Bicycle Light Front Bike Head Light Night Cycling Lamp 5V USB Headlamp Only Lamp No Battery
https://a.aliexpress.com/_mM7Auwx

Quite possibly your light will be limited by your power bank output in that a lot of power banks might only put out 0.5A which is 2.5W and good for around 300 lumens or less. (Whatever they claim about output, it's best to test it yourself as essentially all such stuff is bad quality Chinese junk and the output may be true at purchase but not later , or never was true)

Most usb cables are extremely poorly constructed using conductors of unicorn hair and are sensitive to mishandling

There are various lights such as this for the rear


https://www.magicshine.us/product/tail- ... ke-lights/

But they tend to be designed for coax. You should be able to chop the coax off and solder usb on there instead as the power drivers for these will cope with 5v considering that that is designed for 7.4v input. You can typically find the power driver chip specs online and they will specify, but something designed for 3.7v will probably have a 2-6v input range.

[ConRAD]

... lot of power banks might only put out 0.5A which is 2.5W ...

Thank you.
Modern power banks are however, in many cases, provided of multiple output ports (USB-2.0/3.0) and USB-C this last one capable to automatically adapt output voltage to the connected device up to 18W. The real problem for me is the quality of the light!!

[thelawnet]

... lot of power banks might only put out 0.5A which is 2.5W ...

Thank you.
Modern power banks are however, in many cases, provided of multiple output ports (USB-2.0/3.0) and USB-C this last one capable to automatically adapt output voltage to the connected device up to 18W. The real problem for me is the quality of the light!!

I understand their capabilities but in practice I have had various power banks that don't do what they say, or not for long . I would not trust the spec sheets.

There are plenty of high quality lights that use external cables; the issue is you want something USB which is a bit cheap/Jerry-rigged

Something like this

https://www.lupine.de/products/index/id ... nguage:deu

Takes the input from a Lupine battery pack, which is simply two 18650 cells in series, with a bit of electronics for the charging, and steps it down to 5V.

In your case you have multiple 18650 cells in parallel in your powerbank and a step up converter to 5V.

I'm not too sure about all their electronics, but both Lupine and Hope expect 7.4V

Hope use a more conventional coax cable.

https://www.hopetech.com/products/light ... plus-rear/

There are umpteen million usb to coax cables; e..g my battery charger comes with a usb to coax cable.

So if you found a coax light such as Hope then it might well accept 5V quite happily not withstanding that it's specced for 7.2/7.4V as these digital circuits tend to tolerate a wide voltage range. Whether or not that is the case would depend largely on the sophistication of the light head - one without a battery indicator is less likely to complain, whereas one that does funky things might shut down or flash

[ConRAD]

Well, actually my 20000mAh/74Wh powerpack is going to stay inside the handlebar bag so IPXX is not an issue.
It already comes with 2-off USB-3.0 output ports, 1-off USB_micro input port and 1-off USB-C input/output port personally tested at more than the declared 18W. Furthermore no cable/output port splitter is required.
I’m going to use it for gps/mobile phone and occasionally for unexpected unlit or poorly lit tunnels of which I’m always scared of.
So what I need are good quality 5Vdc front and rear lights independently to be switched-on/of via a suitable handlebar switch panel, the lights will not be rechargeable type and therefore without internal batteries.

[thelawnet]

Well your device is certainly capped at 15W (or less) over 5V judging by your photo which shows that it's sending out 9V for that 19+W.

You haven't given the specs so it's not clear if it will put out 12v or not. But there are lots of lights built for 12v and 6v ebikes which will work directly with either or both

The lights I linked to before expect 7.2v dc - they are not rechargeable.

There are hundreds of ebike lights that expect 6v or more.

This Busch & Mueller effort works with 5V.

https://m.bikester.co.uk/busch-mueller- ... 53825.html

Connection:
Connect by using the wire protruding from the rear light. The wire may be shortened, but never cut off entirely.
When using the rear light with a hub dynamo, it must be connected to the rear light contacts on the headlight. When using a bottle
dynamo, directly connect the rear light to the dynamo.
Please note: Always observe the correct polarity!
Dynamo version:
Black wire: Current (+)
Black/white wire: Mass (–)
Only suitable for 6 V AC voltage
E-bike version:
Black wire: Mass (–)
Black/white wire: Current (+)
Only suitable for 5-15 V DC voltage



So if you cut off the end of a usb cable you'll have four wires, two power and two data. Connect the power wires to that light and it would work perfectly.

As far as your front light goes if you use an actual usb light such as I linked earlier then it should work ok, but if you want to use a e-bike light then your current testing is faulty as you have got 9V through usb-pd negotiation,which with just two wires you can't do.

Try using usb-a rather than C, and sever the data wires (middle two) to see what your real current will be like without the two way communication of voltage signals sent via the data wires.



With just two wires you will probably end up with 5V and somewhere between 1.5A and 2.4A and this is the most you can hope for from USB, because it's vanishingly unlikely that anyone would make a usb-pd/QC bike light that might give you more

Something like this

https://www.bumm.de/en/products/e-bike- ... s7-01.html?

Says it will work with 6-60V and it seems likely that 5V would be ok also. But you would want to use quality cables with reasonably sturdy conductors, not the usual rubbish that comes out of a Christmas cracker, as they do say 7.5W is the goal there.

[ConRAD]

... well it looks to be a mined field!!
however here below a test with a B&M Lumotec alternatively powered with 5Vdc and 6Vac, do you note significant differences?
NOTE: footage speed reduced to 50%

[youtube]qld9ysgCTaM[/youtube]

[thelawnet]

... well it looks to be a mined field!!
however here below a test with a B&M Lumotec alternatively powered with 5Vdc and 6Vac, do you note significant differences?
NOTE: footage speed reduced to 50%

[youtube]qld9ysgCTaM[/youtube]

LEDs are DC.

Typical voltage is 3V, 6V or 12V.

If you have 6V AC then you probably have an LED like this one

https://dammedia.osram.info/media/resou ... .TE_EN.pdf

which is 6V.

Your 6V AC is rectified to 12V DC, which powers 2 x 6V LEDs as here:

https://www.mtb-news.de/forum/t/der-neu ... t-13550927

5V DC might not do the rectifier much good; I would much rather find a DC light without the rectifier circuitry, where the light is built for DC directly as in the case above. At any rate you can step up 5V to 6V if it's outside spec, but I think 5V DC should be ok with most things rated for 6V DC, but not 6V AC.

[ConRAD]

... you haven't given the specs so it's not clear if it will put out 12v or not ...

... apparently yes, here the specs:

TECHNICAL SPECIFICATIONS
Battery capacity: 20000mAh 74Wh
Micro-USB input: DC 5V, 2A
USB-C input: DC 5V, 3A - DC 9V, 2A
USB output: DC 5V, 3A – DC 9V, 2A – DC 12V, 1.5A
USB output: DC 5V, 3A – DC 9V, 2A – DC 12V, 1.5A
USB-C output: DC 5V, 3A – DC 9V, 2A – DC 12V, 1.5A
TOTAL OUTPUT (USB + USB-C): DC 5V, 3A
Dimensions: 145 × 67 × 23.5mm (L×W×H)
Weight: 373g