alan s 

Light & Motion has an interesting 2014 headlight test on its website, allowing you to compare various major brand lights. Shows output over time. Interestingly, the Niterider Lumina 650 I have for commuting (helmet mounted) drops off in lumen output very quickly, whereas others drop more slowly. Says my light starts out at 600 lumens and drops to 400 lumens after an hour. That approximates my experience.

https://www.lightandmotion.com/bike/urban700.html

mstraus

Very interesting. I noticed recently that my Lumina 700 always seems a lot less bright partway into my ride home but didn't realize just how much these lights actually drop off (hard to tell as ambient light is changing plus I cycle between brightness levels at times. It looks like the MagicShine they tested holds it lumens very well. I wonder if the external battery is less likely to make the light overheat.

droy45

I have the same light and its not that it drops off over time. It is programmed to switch to the mid level intensity when it reaches the 20% battery capacity threshold. This helps the light's battery last many more hours otherwise it would run out on you and you would be left in the dark if you continued to use it. Love the feature and always start mine out at night on the mid level when I am in the city with all the street lights and switch to high when I get closer to home on the dark rural route. This method preserves my battery and the light is useful for many hours.

thrllskr

Super Cool, thanks for the share. Cree single LED $21 free shipping off ebay BTW. I looked into the nighthawk 650/700. I am glad I saw this post to confirm looking elsewhere. Thanks

alan s 

The abrupt drop to 100 lumens happens at about 1.25 hours, but prior to that there is a steady decline to 400 lumens. Pretty sure this is with the light on the high setting the whole time. My commute is under an hour, so I never see the abrupt drop, as the light is recharged daily. Good to know there is a lower light level in case I forget to recharge. Running the light on lower settings would save the battery charge for much longer run times. My commute is 95% on dark MUPs, so I generally set on high the whole time. Lots of ninja riders and peds.

droy45

Mine has 3 settings. High, Medium and low. If I run it on high for 1 hour, it depletes the battery down to 20% and it switches to medium. It never switches to low unless I switch it there manually and then I cannot go back to medium or high. It can run on medium for another 2 hours without fading out completely. My commute is 1.5 hrs one way and the light just makes it. If it were any longer I would need 2 lights or get one with the battery packs and spares.

ItsJustMe

I certainly don't want a light that just decides on its own to drop brightness. If run time is a problem either I'll start in a lower brightness mode myself or I'll carry spare lights and batteries. Dropping brightness is a dumb design decision. I don't have a problem with dropping to a really low level when there are 5 minutes left - that gives me a good warning and a little light to see by to dig out the spare battery, but dropping by X percent with lots of time left on the battery is not what I want. I'm riding on very bad streets just 5 minutes from home, and I don't want my light not putting out 100% just when I need it just because I rode for an hour before that.

gregjones

Where did you find the MagicShine??

I was on the 2014 Beam Test but didn't see the MagicShine in the drop down choices.

ben4345

It has a lot to do with driver and heat regulation I believe.

I am always telling people that they should buy a quality light, but no one listens, oh well.
You can test your own lights to see if they have proper output regulation. Get a camera with interval timer, set the camera on manual and adjust your exposure. With a fresh charge have your camera take a photo every minute and look at the histogram. This is also a great way to test the actual battery life of your lights.
Most lights on their "turbo" setting will lose a lot of light due to over heating protection. A lot of lights are not fully regulated, they slowly drop off with use.

ItsJustMe

Doesn't seem like it. Everyone says that the Philips does that intentionally to extend run time. And in some cases the cheapest lights are the ones that maintain brightness the best. I wouldn't think that the $250 Philips would be dropping output because they don't have good drivers and heat regulation.

alan s 

Magicshine MJ808U is in the 800 lumen category, and yes, it does perform very well. 650 lumens for 3 hours.

mstraus

I have three settings as well and I tend to manage it myself a bit too. I don't really need high for most of my commute, so set at low or medium and turn up to high when I really need it. I have noticed at times it seems less bright, but not dramatic. I haven't hit a bit drop off like that to conserve battery yet.

mstraus

The MagicShine was on the Lumen test only, not the beam test. Not sure why they had different list for each test. Go to the lumen test and go to the 800 group.

droy45

How these lights work is when it is at 20% remaining battery life, it switches to a lower intensity so you can still have light. If it would not do that, you would only have a few more minutes and then nothing. I do not consider that a dumb design.

mstraus

It seems the two reason to drop brightness are 1) extend battery life and 2) prevent overheating. Personally I would rather have the light not get damaged from overheating and not have the battery die then be at full brightness the entire time. Ideally the light will be designed well enough to manage heat and battery life to be bright enough for my entire commute though, otherwise I would probably start shopping for a new light.

mstraus

Heat regulation AND extending battery life in some cases. The "slow" drop off over time is more likely due to heat regulation. The sudden drop off at the end is to conserve battery.

I like your idea of using a camera with interval time. The only flaw I can see with this test, and the test that L&M did is that the light is operating on high while standing in place. I would assume some of the heat regulation in these designs assume the light is moving, and therefor has ~15mph or wind going by it which must help with the heat regulation. Standing still seems like it would impact the performance, as well as temperature during the testing.

alan s 

I didn't even look at the beam test. Holy smokes, the Lupine Betty is like riding in daylight!

Andy_K 

The beam test photos seem to come from the 2014 MTBR shootout. The cutover feature on the L&M site is very nice though. It's interesting that it doesn't strictly favor their lights. For instance, comparing the NiteRider Lumina 650 to their Urban 700 I see that the Urban 700 has better near-field illumination but the Lumina lights up the distant target better. It's nice to visualize the trade-offs in beam pattern. I really wish they had a beam shot for the MagicShine. I found it on last year's MTBR shootout, and it looks like it has a pretty tightly focused beam, but I'd like to be able to see it with the cut-over.

The differences in beams also makes me wonder how the lumens were measured.

gregjones

Thanks. Found it!!

I just gave up before I got that far.

gregjones

I hear that the MagicShine is very similar to the twenty buck CREE lights on Amazon-----not having ever seen a MagicShine in the flesh I can't say so from personal experience.

The CREE light is a tight spot. I got one of the $6 wide angle lens and like it a lot better. It's alright for all of my out-in-the-sticks riding with the exception of the lower parts of the few 30+ mph hills. I've never been in town at night with it. As cheap as they are, I might get another and leave the factory lens in it. I think that would work great for a $50 light investment.

gregjones

It better do something for almost $1200!!

ben4345

Lumens should be measured with integrated sphere.