Is it possible to run a dynamo-based LED light from a battery pack?

steverosburg · Jul 26, 2010

Hi,

I am interested in getting a high-quality dynamo-driven light with a glare-free pattern like the Supernova E3 Pro; however, I don't have a dynohub, and it will cost me over $400 to get a new 20" front wheel built for my recumbent with a Schmidt SONdelux hub.

So, I am curious whether it is possible to power a dynamo light like the Supernova E3 with a 6V battery pack instead of a dynamo, at least until I can afford a new wheel built with a dynohub? I realize that a dynamo produces AC rather than DC, but that's about the extent of my knowledge. Would a DC power pack work, and would it be safe for the light?

My goal is to be able to ride before dawn and see everything in the road in front of me, including minor stuff like gravel, etc. I need something that will illuminate the road evenly without a dark spot right in front of the bike, be bar-mountable, and last for at least 2 hours. I am open alternate suggestions on an inexpensive way to accomplish this, but I'm really not interested in building something myself unless it involves only a really simple/minor modification to something out there. I have no experience with these new super bright LED lights, so I really don't know how bright is "bright enough", but based solely on other people's reviews, the Supernova E3 Pro seems to do the job splendidly, so I was thinking of something in the 300 lumens range.

Any help you can provide is much appreciated.

-Steve

znomit · Jul 27, 2010

The inoled runs off of dyno or battery
http://www.peterwhitecycles.com/inoled.asp

steverosburg · Jul 27, 2010

Thanks! The Inoled Extreme looks like it may suit my purposes well, I'll look into that light more.

[Edit] After doing a little more research, the Inoled Extreme seems a bit outdated by today's standards. It's primarily plastic rather than aluminum, and it's rated at 100 lumens, quite a bit lower than some of the newer ones. I've read some reports of failure as well.

steverosburg · Jul 27, 2010

One other possibility would be to create an inverter circuit to convert a 6V battery pack from DC to AC, but without the step-up transformer. I'm not an EE so I'm not familiar with what's involved, but a co-worker who has a background in EE says it should be pretty straightforward with using a FET-based design.

Has anybody else already designed such a circuit for this purpose? It obviously would have very low power requirements. I was thinking if I could use a 6V power pack (e.g. 5x1.2V NiMH batteries) it would power a 3W light like the Supernova for a good long time.

BrianMc · Jul 28, 2010

OK I am no EE either.

The 12 volt AC/DC landscape/interior LED light modules have a rectifier to convert the AC, yet they handle DC just fine. There is some inefficiency over a DC-only driver with no rectifier, but to add an inverter to make AC only to convert it back to DC is even more energy waste.

There may be a standlight capacitor in the light that is not needed but I don't see the harm other than the light is on after the battery is switched off or unplugged, for maybe 30 seconds or so.

I assume you have Googled this forum for old threads on this topic. Even if they are older LEDs the principles are the same.

Another forum to Google (though I find it harder to extract good stuff there) is here.

steverosburg · Jul 28, 2010

Brian,

Thanks. I contacted Supernova and they said that it won't work -- whether that is because it's merely not supported, or will actually not function and/or cause harm I can't say. I wish I had a way to test without shelling out lots of money and risking possible harm.

On the plus side, Supernova just announced the Airstream, which is a battery-powered unit based on a similar head design as the E3 Pro glare-free, but uses the new Cree XPG R5 emitter for a claimed 370 lumens off a single 18650. I might just wait and see how much that is when it hits the shelves in the US in a couple months.

HOLONYAK · Aug 1, 2010

There is no good reason that you cant build a power supply for your light. I, too, am no EE...but logically it CANNOT be that difficult. However, when I posted the same question here, I decided it was too intimidating. I think the Ixon IQ Speed is a nice battery friendly light.

unterhausen · Aug 1, 2010

steverosburg said:
Brian,

Thanks. I contacted Supernova and they said that it won't work -- whether that is because it's merely not supported, or will actually not function and/or cause harm I can't say. I wish I had a way to test without shelling out lots of money and risking possible harm.

it would not be at all surprising if it simply didn't work. If you look at most of the dyno circuits on Pilom, you will see the input goes through capacitors. That would block battery voltage and you simply wouldn't get any light.

BrianMc · Aug 1, 2010

unterhausen said:
it would not be at all surprising if it simply didn't work. If you look at most of the dyno circuits on Pilom, you will see the input goes through capacitors. That would block battery voltage and you simply wouldn't get any light.

Forgot the smoothing and standby capacitors.

If the circuit board is a separate unit, I suppose it could be removed along with the stand by capacitor and a battery LED driver substituted.

If theres's a will...and enough money and time...

swhs · Aug 1, 2010

steverosburg said:
Hi,

I am interested in getting a high-quality dynamo-driven light with a glare-free pattern like the Supernova E3 Pro; however, I don't have a dynohub, and it will cost me over $400 to get a new 20" front wheel built for my recumbent with a Schmidt SONdelux hub.

So, I am curious whether it is possible to power a dynamo light like the Supernova E3 with a 6V battery pack instead of a dynamo, at least until I can afford a new wheel built with a dynohub? I realize that a dynamo produces AC rather than DC, but that's about the extent of my knowledge. Would a DC power pack work, and would it be safe for the light?

My goal is to be able to ride before dawn and see everything in the road in front of me, including minor stuff like gravel, etc. I need something that will illuminate the road evenly without a dark spot right in front of the bike, be bar-mountable, and last for at least 2 hours. I am open alternate suggestions on an inexpensive way to accomplish this, but I'm really not interested in building something myself unless it involves only a really simple/minor modification to something out there. I have no experience with these new super bright LED lights, so I really don't know how bright is "bright enough", but based solely on other people's reviews, the Supernova E3 Pro seems to do the job splendidly, so I was thinking of something in the 300 lumens range.

Any help you can provide is much appreciated.

-Steve

The best dyno light is the Edelux (which does have a short dark spot in front of the wheel). The Cyo Nahfeld would be an alternative (no dark spot). However, if you are prepared to use batteries this might be of use: I just did my first test run with the Philips LED bike light (claimed 270 lumen on the road, compared to a measured 180 for the Edelux) and I was astounded by how much brighter and further it lights up the road than the Edelux. It also blows away Kerry's triple XP-G (see http://www.cncdelite.com) and the Magicshine for on-road use. More information, pictures and beamshots (probably with my old but also with a new camera), to come on my lighting test page. I'll be testing a Sanyo dynohub too. I look forward to comparing it to the Shimano DH-3N80. And I will test a few crappy halogen/low power LED headlights, just for fun

Weg page (additions to come later this week):

http://www.xs4all.nl/~swhs/fiets/tests/verlichting/index_en.html

steverosburg · Aug 2, 2010

swhs said:
The best dyno light is the Edelux (which does have a short dark spot in front of the wheel). The Cyo Nahfeld would be an alternative (no dark spot). However, if you are prepared to use batteries this might be of use: I just did my first test run with the Philips LED bike light (claimed 270 lumen on the road, compared to a measured 180 for the Edelux) and I was astounded by how much brighter and further it lights up the road than the Edelux. It also blows away Kerry's triple XP-G (see http://www.cncdelite.com) and the Magicshine for on-road use. More information, pictures and beamshots (probably with my old but also with a new camera), to come on my lighting test page. I'll be testing a Sanyo dynohub too. I look forward to comparing it to the Shimano DH-3N80. And I will test a few crappy halogen/low power LED headlights, just for fun

Great, thanks for the tip! I think the new Supernova Airstream will be pretty awesome as well -- it claims 370 lumens and has an asymmetric beam pattern, and it can be charged on-the-fly via mini-USB connection. That way, on those rare occasions where I need it on high for more than 2.5 hours, I can just bring along a USB battery pack with 4xAA NiMH batteries to help augment the internal battery.

swhs · Aug 2, 2010

steverosburg said:
Great, thanks for the tip! I think the new Supernova Airstream will be pretty awesome as well -- it claims 370 lumens and has an asymmetric beam pattern, and it can be charged on-the-fly via mini-USB connection. That way, on those rare occasions where I need it on high for more than 2.5 hours, I can just bring along a USB battery pack with 4xAA NiMH batteries to help augment the internal battery.

The Philips light also has a USB charge connector.

Further note that the XP-G doesn't give 370 lumen, at least not at 1A which I presume they're driving it at (assuming losses in the electronics, the 9.25 Wh they mention for the battery should be enough for the 2.5 hours they also mention, when driving the XP-G at 1A but almost certainly not more. And at 1A the XP-G produces ca. 270 lumen max. (measured), as opposed to 370 lumen (Cree fantasy value). See:

http://www.mtb-news.de/forum/showthread.php?t=298107&page=44

and in particular this posting:

http://www.mtb-news.de/forum/showpost.php?p=6822716&postcount=1088

(All done with proper testing equipment).

So, 270 lumen minus losses is probably 240 max out-the-front.

As to the Philips light, I get the feeling it puts out more light than 270 lumen, as it gives so much more light than the Edelux. The beam is noticably wider and brighter and longer. Could be apparant due to the slightly greenish LED colour used in the Edelux (there are advantages for this greenish colour btw.) just like a cool white light appears brighter than a neautral one of the same output, but I'm not sure yet.

Anyway, my guess is that the Philips light is superior to the Supernova (incl. the beam pattern).

Oh yes, I and the guy I have the Philips light on loan from, rode with various lights comparing the Edelux, Kerry's triple XP-G (dyno powered), the Philips light and an old halogen and compared them all. We both felt that the Philips gave an extremely good illumination and we both had the idea that more light was not needed, in fact, switching back to low mode was easier on the eyes sometimes, for example due to little posts on the side of the road with reflective material. With the Philips light in high mode they reflect so much it's almost annoying... I'll do more comparison tests this week. Philips' claim of a throw of 80 metres looks reasonable: I'd say, ca. 70 m. from my first test. With the Edelux and the triple XP-G I get ca. 45 m.

steverosburg · Aug 3, 2010

swhs said:
The Philips light also has a USB charge connector.

Further note that the XP-G doesn't give 370 lumen, at least not at 1A which I presume they're driving it at (assuming losses in the electronics, the 9.25 Wh they mention for the battery should be enough for the 2.5 hours they also mention, when driving the XP-G at 1A but almost certainly not more. And at 1A the XP-G produces ca. 270 lumen max. (measured), as opposed to 370 lumen (Cree fantasy value). See:

http://www.mtb-news.de/forum/showthread.php?t=298107&page=44

and in particular this posting:

http://www.mtb-news.de/forum/showpost.php?p=6822716&postcount=1088

(All done with proper testing equipment).

So, 270 lumen minus losses is probably 240 max out-the-front.

As to the Philips light, I get the feeling it puts out more light than 270 lumen, as it gives so much more light than the Edelux. The beam is noticably wider and brighter and longer. Could be apparant due to the slightly greenish LED colour used in the Edelux (there are advantages for this greenish colour btw.) just like a cool white light appears brighter than a neautral one of the same output, but I'm not sure yet.

Anyway, my guess is that the Philips light is superior to the Supernova (incl. the beam pattern).

Oh yes, I and the guy I have the Philips light on loan from, rode with various lights comparing the Edelux, Kerry's triple XP-G (dyno powered), the Philips light and an old halogen and compared them all. We both felt that the Philips gave an extremely good illumination and we both had the idea that more light was not needed, in fact, switching back to low mode was easier on the eyes sometimes, for example due to little posts on the side of the road with reflective material. With the Philips light in high mode they reflect so much it's almost annoying... I'll do more comparison tests this week. Philips' claim of a throw of 80 metres looks reasonable: I'd say, ca. 70 m. from my first test. With the Edelux and the triple XP-G I get ca. 45 m.

Thanks for the additional info!

[Edit]: I can't seem to find the Philips LED bike light listed anywhere here in the USA; the only place I see it listed is bike24.com. Is it available via a US distributor?

panicmechanic · Aug 3, 2010

swhs said:
The Philips light also has a USB charge connector.

Have you tried charging on the fly? Among the few information I have, I read that charging input makes the light shut off, thus preventing the use of an external USB battery. Don't know if that would work with internal batteries removed.
Exchanging the batteries requires a tiny screwdriver, not ideal in the dark. So the runtime is, and is likely to stay, somewhat limited, unless you replace or modify the electronics.

As for the Cyo/Edelux: these can be run from a battery. You must not feed more than 7.5 Volts into the light. The safest way would be to determine the current at that voltage and buy a constant current driver made for that current.
In my case, one of the DX 1 Watt drivers was perfect to give 300 mA.

Please note that DX is not the place to buy high quality products, so you'd better buy a few of those and pick the one that suits your light's needs best.

And then, those lights will not shine as bright on batteries as they would on a dynohub.

BrianMc · Aug 3, 2010

steverosburg said:
I can't seem to find the Philips LED bike light listed anywhere here in the USA; the only place I see it listed is bike24.com. Is it available via a US distributor?

I didn't find one when I read this post in the design a road beam thread and saw the beamshots:

https://www.candlepowerforums.com/posts/3292123&postcount=201

It would seem to be a natural for Peter White although the B&M and Schmidt sources may be happy he doesn't. His light page was updated in March, so maybe he does now.

A video of it:
http://www.youtube.com/watch?v=lej8pbR5RDQ

No US dealers come up on first 2 pages of Googling 'Philips LED bicycle light' It appears to have been released a year ago this fall as their first bike light, which may be part of the problem with distribution in the US.

Maybe Peter White has connections and can get one for you. Otherwise, you'd be forced to buy from Bike24 or the Danish site and have it shipped.

steverosburg · Aug 4, 2010

BrianMc said:
I didn't find one when I read this post in the design a road beam thread and saw the beamshots:

https://www.candlepowerforums.com/posts/3292123&postcount=201

It would seem to be a natural for Peter White although the B&M and Schmidt sources may be happy he doesn't. His light page was updated in March, so maybe he does now.

A video of it:
http://www.youtube.com/watch?v=lej8pbR5RDQ

No US dealers come up on first 2 pages of Googling 'Philips LED bicycle light' It appears to have been released a year ago this fall as their first bike light, which may be part of the problem with distribution in the US.

Maybe Peter White has connections and can get one for you. Otherwise, you'd be forced to buy from Bike24 or the Danish site and have it shipped.

Nah, I'm not going to bother with it if it's this hard to come by. I've sent e-mails to Peter White before and gotten no response, so I'm really not interested in giving him my business, and there's no way I am going to pay $100 or more for shipping on something that cost $150. The Supernova Airstream should meet my needs perfectly and will be available in September, I've got my name on a waiting list with a US distributor.

swhs · Aug 4, 2010

steverosburg said:
Nah, I'm not going to bother with it if it's this hard to come by. I've sent e-mails to Peter White before and gotten no response, so I'm really not interested in giving him my business,

That's sort of thing (well, slightly different) is my reason for not doing business with Supernova...

steverosburg said:
and there's no way I am going to pay $100 or more for shipping on something that cost $150.

Come on! The bike24.net website says 20 euro, so for about $160 total you could have the Philips LED bike light.

I've done some more tests with it on a wettish surface, again excellent, I'm writing it all up and making pics, I'll probably have it on my website by friday.

steverosburg · Aug 4, 2010

swhs said:
That's sort of thing (well, slightly different) is my reason for not doing business with Supernova...

So far, I've had nothing but good experience dealing with them regarding e-mail inquiries.

swhs said:
Come on! The bike24.net website says 20 euro, so for about $160 total you could have the Philips LED bike light.

My bad! I didn't actually check what the shipping was on the bike24.com, or I would have realized the fixed-cost shipping (which is not bad). I've experienced some outrageous shipping costs from Germany in the past, so I just assumed this would be the same.

swhs said:
I've done some more tests with it on a wettish surface, again excellent, I'm writing it all up and making pics, I'll probably have it on my website by friday.

Great, I look forward to it. Also, how does the light deal with heat build-up and dissipation, and how is the build quality? If it dropped, would it survive?

swhs · Aug 13, 2010

steverosburg said:
So far, I've had nothing but good experience dealing with them regarding e-mail inquiries.

My bad! I didn't actually check what the shipping was on the bike24.com, or I would have realized the fixed-cost shipping (which is not bad). I've experienced some outrageous shipping costs from Germany in the past, so I just assumed this would be the same.

Great, I look forward to it. Also, how does the light deal with heat build-up and dissipation, and how is the build quality? If it dropped, would it survive?

I have it on loan, so I'm not going to drop it. But it looks extremely sturdy. the housing is a gigantic piece of curved aluminium, so it can withstand a lot and it's a giant heatsink with lots of surface area as well. On high it gets a little warm (lukewarm) after several minutes at room temperature. While riding it never got warm as one would expect which such a large surface area. The weakest part w.r.t. dropping it is probably the plastic lens, but I'm not sure what that can withstand without testing.

As to an earlier question about charging: I don't have the charger, so I don't know if the light can be used while charging. {Edit: I use the Maha 9000 to charge the batteries out of the case )

Other questions please in the thread I'm about the make, as this light deserves a separate thread ;-)

markus_i · Aug 14, 2010

swhs said:
Come on! The bike24.net website says 20 euro, so for about $160 total you could have the Philips LED bike light.

Maybe less, actually:

The light sells for 100 Euros. Deduct 20% (actually 19%, but keep it simple) German VAT (see footnote 2 on the shipping cost page - all advertised prices in Germany have to include VAT), add 20 Euros shipping for a total of 100 Euros, which is currently 130 USD.
Add your carriers' customs clearance fees and any import duties and local taxes at your end.

Bye
Markus (tempted myself, although I don't even have a bike for the light - all our bikes have generator hubs, but see the other thread...)

Is it possible to run a dynamo-based LED light from a battery pack?

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