Lights

[morphix]

Incredible. I got to get one. There's some well dangerous places where I ride at night, middle of nowhere, no street lights, nothing, and water, lots of water..rivers and lakes..I was riding home one night around this lake by just the moonlight cuz my bike light was doing nothin.. I had my nokia n810 on the handlebar giving a reassuring little glow from the LCD but the SatNav showed me as being in the lake..I was like...wut! I looked down..everything felt dry, so I carried on lol

 

[Scimitar]

Have you got a lux meter? It would be interesting to see what the reality of lumens is compared to the makers' claims. There is really tons of light there but a benchmark of actuality would be handy for comparison when it comes to choosing lights - a BS factor to apply to makers' figures, if you will.

 

[Deleted member 4366]

Numbers doon't really mean anything. The 3 LED torches are about the same as a car headlight. That's all you need on a bicycle. The one LED ones would be adequate for most people.

 

[Old_Dave]

Bright enough for a rabbit shoot

Stuff the wabits.. its foxes and deer

Opppppppppsss lamping deer is verboten, just the foxes then

 

[grldtnr]

you should bee safe from the 'SMIDSY' syndrome ,I don't see how they could miss you.

 

[banbury frank]

We use these if you need more fit 2 will work on 12 to 80V

3W High Power LED Spot Light for Motor E-Bike(63mmx52mm ) | eBay

Frank

 

[Deleted member 4366]

We use these if you need more fit 2 will work on 12 to 80V

3W High Power LED Spot Light for Motor E-Bike(63mmx52mm ) | eBay

Frank

They're not bad, Frank, but not in the same league as the single Cree T6 XML lights - let alone the tripple one mentioned above.

 

[Scimitar]

Numbers doon't really mean anything. The 3 LED torches are about the same as a car headlight. That's all you need on a bicycle. The one LED ones would be adequate for most people.

So, even you don't believe it's 18,000, then?

 

[Jeremy]

There's an easy check on these claims. The very best possible luminous efficacy is 683 Lm/W, that's from a perfect emitter. The best LEDs available are usually around 170 lm/W (Cree have claimed 200 lm/W for their very best LEDs), so an 18,000 lm lamp would draw around 106W or thereabouts. In reality, most readily available LEDs struggle to manage more than around 120 to 150 lm/W, often less when driver and battery IR losses are taken into account.

Knowing these numbers allows a reality check on some of the more outrageous claims, provided you can measure or assess the power being drawn.

 

[Deleted member 4366]

So, even you don't believe it's 18,000, then?

According to the Cree datasheet, the T6 gives about 350 lumens at 1 amps, about 700 at 2 amps, and it can take a maximum of 3 amps, so 1000lumens is possible. I've no idea how many amps these torches push through them. As I said before, how many lumens is irrelevant. For comparison, one t6 = moped headlight and three T6s = bright car headlight. That's all anyone needs to know.

 

[morphix]

According to the Cree datasheet, the T6 gives about 350 lumens at 1 amps, about 700 at 2 amps, and it can take a maximum of 3 amps, so 1000lumens is possible. I've no idea how many amps these torches push through them. As I said before, how many lumens is irrelevant. For comparison, one t6 = moped headlight and three T6s = bright car headlight. That's all anyone needs to know.

That's a lot of current for LEDs to draw! I'm interested Infrared LED's lately.. those can draw just as much energy, super bright, but invisible to the naked eye of course.."black light"..not much use on a bike unless you use an electronic viewfinder or summat

 

[Jeremy]

It is a lot of current, and the LEDs get pretty hot! I've made a few LED lamps and a couple of torches, and you need to seriously heatsink these bright LEDs to stop them from cooking.

A typical 3W rated LED will run at around 800mA or so (the forward voltage drop is usually around 3.7V or thereabouts). Around 2/3rds or more of that power will be wasted as heat, so they do run hot if not carefully mounted.

Having said that, they are cooler running than incandescent lamps by a long way, because of the greater efficiency. Generally, LEDs are around the same sort of efficiency as CFL bulbs (the low energy household bulbs).

If you want to build a really powerful bike light, to run from the bike battery, then there is some merit in looking at using a larger number of lower power (and cheaper) LEDs. For example, using an array of 9 1W LEDs in series gives a forward voltage of around 33 to 34V, and would draw a current of around 300mA or so, and if you had a 36V battery you could get away with using a simple 10 ohm, 1W resistor as the current limter, with no need for an LED driver. You'd get a LOT of light from such an array, around 1000 lm or maybe more, with a nice wide spread. It'd be fairly cheap, too, if you're good with a bit of DIY.

 

[Scimitar]

According to the Cree datasheet, the T6 gives about 350 lumens at 1 amps, about 700 at 2 amps, and it can take a maximum of 3 amps, so 1000lumens is possible. I've no idea how many amps these torches push through them. As I said before, how many lumens is irrelevant. For comparison, one t6 = moped headlight and three T6s = bright car headlight. That's all anyone needs to know.

I need hardly remind you it was you who bandied the 18000 figure about, nobody else. If you're going to quote such figures, please back them up or at least take them with a pinch of salt.
As I've said, there's one helluva lot of light there and I'm not complaining about the lack of it and would certainly be happy with half or even a third of that.
I see no merit in repeating the manufacturers' bull sheeit though - it only encourages them.

 

[Deleted member 4366]

I need hardly remind you it was you who bandied the 18000 figure about, nobody else. If you're going to quote such figures, please back them up or at least take them with a pinch of salt.
As I've said, there's one helluva lot of light there and I'm not complaining about the lack of it and would certainly be happy with half or even a third of that.
I see no merit in repeating the manufacturers' bull sheeit though - it only encourages them.

Well. Ive got the 9LED one coming soon. If I add that and take another photo, will that make you happy?
The 9 LED one is advertised at 11,000 lumens on its own.

 

[Scimitar]

Well. Ive got the 9LED one coming soon. If I add that and take another photo, will that make you happy?
The 9 LED one is advertised at 11,000 lumens on its own.

What I'm gettting at is ... trying to get a measure of how much the makers are exaggerating their figures. You have a good selection of lights and might be the very man to find out with a lux meter.
Who knows - perhaps one or two don't exaggerate and it would be nice to know who they are.
Fore-armed with this correction factor it would be possible to evaluate some of the other makers' claims before spending money on lights which might or might not live up to expectations.

 

[Jeremy]

The 9 LED one is advertised at 11,000 lumens on its own.

I hate to say this, but that sounds a bit OTT to me. 9 off 20mm puck LEDs will run at around a total power of 25 to 30 watts, maybe less because of the difficulty in getting heat out of the inner LEDs in the array effectively.

30W, even using the best Cree LEDs around is only going to deliver about 6000 lm. In all probability the light output is more likely to be a lot less. A typical 9 LED motorcycle type headlight using 3W LED pucks is usually around 2000 lm.

You can certainly get arrays that will put out this sort of light, but they aren't as easy to focus as the spot source LEDs usually used in lamps and torches. I've got a big Bridgelux array on order (100W and 9000 lm, but can be over-run a fair bit with a good heatsink, apparently). The problem is that it ends up giving a pretty broad beam, because the emitter is a large flat array, rather than a point source.

 

[Deleted member 4366]

I hate to say this, but that sounds a bit OTT to me. 9 off 20mm puck LEDs will run at around a total power of 25 to 30 watts, maybe less because of the difficulty in getting heat out of the inner LEDs in the array effectively.

30W, even using the best Cree LEDs around is only going to deliver about 6000 lm. In all probability the light output is more likely to be a lot less. A typical 9 LED motorcycle type headlight using 3W LED pucks is usually around 2000 lm.

You can certainly get arrays that will put out this sort of light, but they aren't as easy to focus as the spot source LEDs usually used in lamps and torches. I've got a big Bridgelux array on order (100W and 9000 lm, but can be over-run a fair bit with a good heatsink, apparently). The problem is that it ends up giving a pretty broad beam, because the emitter is a large flat array, rather than a point source.

Check-out the Cree datasheet if you want to know anything about them.
http://www.cree.com/~/media/Files/Cree/LED Components and Modules/XLamp/Data and Binning/XLampXML.pdf

Scimitar, I don't have a lux meter. Each single T6 LED is about the sane brightness as the next at the same voltage. I bought one single Cree t6 bikelight that runs on 4.2v instead of 8.4v like a previous one and it wasn't as bright. I can't remember the figures, but the advert showed fewer lumens. All the others are about the same whether you have them in a torch or a bike light.

The single T6 torches are also pretty good. They're adequate for unlit cycle-paths etc, but for unlit roads, you need a bit more presence, so I'd advise the triple one. The torches are really easy. They have internal Ultrafire rechargeable batteries, so you fit a handlebar clamp and away you go. For the larger 3 LED torches, you need one of those "T" handlebar extensions and two clamps unless you can find a sturdy one the right size.
Bicycle Bike Handle Bar Extension Expand Light Speedometer Mount T Type | eBay
Flashlight Mount Holder For LED Bicycle Bike Torch Clip | eBay
1600 Lumen Zoomable CREE XM-L T6 LED 18650 Flashlight Torch Zoom Lamp Light | eBay
2 x Ultrafire 18650 LI-ION 2400mAh 3.7V Rechargeable BATTERIES + Travel Charger | eBay

 

[Jeremy]

Check-out the Cree datasheet if you want to know anything about them.
http://www.cree.com/~/media/Files/Cree/LED Components and Modules/XLamp/Data and Binning/XLampXML.pdf

As I've been building LED lights for a while I have all the data sheets, thanks..........

If you look at the data sheets you'll see that the best bin emitters can get to around the lm/W figures I quoted, after optical losses. This is the reason that I question the 11,000 lm claim from 9 LED pucks, it doesn't stand up well to a bit of careful scrutiny, does it?

I mean, take a U2 bin cool white XM-L as an example. 300lm at 3W, so only 100 lm/W (these aren't the best LEDs, either). The higher current outputs aren't measured, they are estimated, in part because it gets hard to get the heat out of the puck in an array. An 11,000 lm 9 LED torch would need more than 1200lm per LED. In fact, if you allow for the losses in the optics it'll be more than that.

The figures quoted just don't seem to stack up to me, based on my limited experience of making these things. If it really does have 1200lm plus LEDs in it, then that suggests they are around 6W apiece if they are double the lm/W spec of the XM-Ls you quoted, which is possible, but not very likely I'd have thought.

 

[Geebee]

It's pointless getting hung up on the Lumens, just use them as a guide once you have one type of LED then you can then use the rating to decide if it will be brighter or not
I hope the the 9 LED monster has a good sized battery pack, that sucker will draw some serious current.

 

[morphix]

It's pointless getting hung up on the Lumens, just use them as a guide once you have one type of LED then you can then use the rating to decide if it will be brighter or not
I hope the the 9 LED monster has a good sized battery pack, that sucker will draw some serious current.

He probably has two batteries, one for his motor and one for his lights ;-) His light obsession is almost as bad as mine and Kitchenman's camera obsessions, I can't stop buying them, got quite a collection now! Everything from keyring cams, pocket cams, to big old camcorders..and state of the art night vision CCTV...they just fascinate me.