Rhodabike

I'm in the market for a brighter lighting set and am confused by some of the lighting terms I see on the manufacturers packaging. One claims "400 candlepower", another claims "200 lumens", others don't seem to mention brightness at all. How does candlepower compare to lumens?

buzzbee

candlepower - light intensity at a distance
lumen - light energy over a volume
https://www.theledlight.com/lumens.html

not so helpful in choosing a light
10-50 lumens give you a "be seen" bike light, or perhaps enough on a bike path
200-2000 lumens give you enough light to see where you are going at 15 mph or faster.
I use a 200 lumen setting on the MS light most of the time, I also have 4 other flashlights available to turn on.

So share the conditions you will ride in, there are plenty of expert around here.

Rhodabike

Mostly suburban streets and a section of pathway. The street lights are shrouded by old trees for much of the suburban part.
The basic commute is only 4.5 kilometers. The increased need comes if I want to get a swim in before work, which triples the distance and includes a completely unlit and unpaved section between two paths. It's a goat track, really - for some reason the city has not extended the two paths to meet each other, and riding on the road between would mean going the wrong way into traffic.
Can an led light offer 200 or more lumens? I've heard that a single high intensity led can actually be better than multiple leds packed into a headlight. I've gotten by with two multi-led headlights either side of the stem, one aimed low, the other a bit higher, but have had to slow down quite a bit to see properly.

colleen c

First the bad news. there is no accurate ways of converting Lumen and candlepower.

Good news, most bike lights manufactor uses lumen as the measurement, but....... even that value can be differ depending on the manufactor. The better quality company such as Cygolight and Nightrider rating are more accurate while lots of the China made light such as P7 and MS are rated higher than the actual output if you put them side by side with a light from Nitrider with the same lumen. One thing I learned over my course of light shopping is to buy more lumen than needed as long it has a mode switch that can run them on a lower setting. You can use what you need and turn it up when the condition arises.

Yes, Led light does offer 200 or more lumens. Most bike light these day are LED. They differ only by what type of LED they use in the light head. You can have a low simple intensity LED like the type they use on small blinkie or Knog light. On the other end of the extreme, you can have LED emitter such as a P7 or SST50 which are much more brighter and more powerful.

I'm not sure what type of led healight you were using but I can probably say that most likely the one that is aim high might not be doing much at all. Keep in mind that the spread of the light dimish rather quickly at a farther distant. The only way to get by this is to have a better reflector that has a better pinpoint focus and thus "throw better", however without some good lumen behind it, you will not get much of a wide coverage (imagine a laser pointer). Most lights these day have more of a flood than throw because of the reflector design to keep the lighthead compact and small. That's why I prefer to have more lumen than I needed. I can choose the lower setting and get the flood in front of me and when needed, I can go to the high mode and get a farther throw without losing too much of the flood of lights closer to the front of me.

What light are you presently using? This might give us a better idea of how much more you will need.

Richard Cranium

In the old days there was a good old measure of power - it's called Watts!

And try to understand one other thing when shopping for a light - if it is not using at least a 6V or 7.2V power source then it should be considered either a very short run time or very dim light.

In other word, except for some exotic flashlights you need a 4xAA (6Volt) or Lithium Ion battery source.

Too bad more dealers don't let you "demo" ride lights - in real ride circumstances.

Raptor1956

If all lights used the same type of light source Watts might be a good way to compare but not all types of lights are equally efficient. In the home a florescent light of 11W maybe bright and put out more total light power than a 60W incandescent bulb.

Also, the voltage of the battery is of less importance than the energy (WHrs) so long as the battery can deliver the required power for the required duration it makes almost no difference what the battery voltage is because modern electronics can convert it to whatever voltage is needed.

Most of the current lights are LED because they are more efficient than incandescent and even HID. I think florescent would be comparable in efficiency but the bulb shape would make producing a highly directional beam less practical in a small package. LED is also desireable because they are not nearly as vulnerable to vibration and bumping you experience riding a bike, particularly a mountain bike. Most lights have rechargeable batteries and most of them are sealed units that are designed to limit the use of cheap replacement batteries so you buy from them.

I have a 7 year old HID that's finally giving out and I plan to get a decent LED in the 600 lumen range.


Brian

Richard Cranium

No, of course it does - you either give up run time, or simply don't power the light well.

And no doubt, they both will run from a 6V or more source.......

For the sake of discussion I was referring to luminous watts. But for anyone who cares, if you know anything about modern LEDs then you'll know you'll want or need an LED that draws at least three watts of power. And that - ladies and gents means you'll want some batteries.........

As far as the original thread is concerned - knowing bike lighting "terms" still won't guarantee satisfaction because there is more to the quality of any lighting system than numerical specs. But my experience suggests that if you need to "see" anything for any length of time you'll need a more powerful system. And they are generally six or more volts.

buzzbee

riding on a dark bike path..., I would think that seeing the path and any obstacles well is most important. you could get a 180 lumen flashlight, like the Fenix L2D, LD20, or similar, or the Magicshine which gives you the option of even more light if you need or want it. I have bike path sections on my commute where I can surprise a skunk, so having a good light helps me prevent a smelly situation by stopping/slowing in advance. So, it depends on your conditions, how fast you want to ride, etc... Remember to aim the light at a point on the ground perhaps 20-30 ft in front of the bike so as not to blind others.
That's the other part about rating lights, it's not just the optical power produced, but the dispersion pattern the light is produced in. You want more light illuminating the road, and less blinding others, just like car headlights have been designed to do.

Raptor1956

Well you have your terms confused, that's for sure. So, let's go through this shall we...

A 6V battery with only 100mAHr capacity will likely provide less light for a shorter time than a 2.4V battery with a 1000mAHr capacity. The first will have an ENERGY of 0.6WHr while the second will have an energy of 2.4WHr or 4X as much energy! The power supply only needs to provide a voltage to your lamp that's high enough to produce maximum power when the battery is at it's lowest state of charge. In practice, the electronics modulates the output from the battery or power supply so that it provides a constant voltage to the lamp no matter what the battery voltage is.

It likely true that most of the more powerful lights will have a voltage of 6V or more because they will use multiple cells in series. With a typical lithium cell at about 3.6V if you put four in series you'll wind up with over 14V. If, OTH, the lamp, say an LED, requires, say, 3.3V to produce maximum power then the electronics will modulate the output of the battery so that the voltage the LED sees is 3.3V. Doing it this way allows the battery to drop in voltage, as they all do, but keep the voltage to the LED constant. Now if you want the LED to operate at lower power, say medium, then the electronics will modulate the power from the battery so that the LED see's a lower voltage than on high.

It is surprising how many people confuse simple terms. Voltage is not current. Voltage is not power. Voltage is not energy. Here's the relationship:

P = VI and E = Pt

P = power, V = voltage, I = current and t = time

So, the voltage of the battery pack, by itself, is meaningless as is the Ampere*hour rating. But, if you put the two together you get the energy of the battery and that is important. Again, with modern electronics you can take almost any voltage and make almost any voltage you want. You can, for example, take a 1.2V cell and make a supply that outputs hundreds or even thousands of volts from it and you probably have one on your camera.

So, if you need to output 10W for 3 hours you need a battery pack of 30WHrs or more and it doesn't really matter if that is done using a pack of 3.6V and 8333mAHr or a battery of 14.4V and 2083mAHr or a battery of 24V and 1250mAHr or even 1.2V and 25AHr.

One of the big reasons the light makers have switched to LED is that they are more efficient than other light types so you do not need as big a battery pack. There are other advantages, such as being less prone to damage from shock/bumps.


Brian

colleen c

There is one advantage of higher voltage. Personally I prefer the a higher voltage and lower amps draw for any given requirement. A higher volatage sometimes means less current draw which is easier on the battery pack which the Internal Resistant of the battery may affect the overall performance. So in the case where the power consumption is 10w, I rather draw 1.35amps with a 7.4v pack instead of having to draw 2.7a from a 3.7v source in which case some battery cannot provide because the internal resistant is the limiting factor. Also less amp draw on the pack means less heat on the pack and sometime better efficiency depending on the application. Then off couse all this will depend on the load and how it is set up for the input voltage requirement.