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Nitefighter BT21 2x XM-L2 NW light

193K views 2K replies 137 participants last post by  MRMOLE 
#1 · (Edited)
As you guys are starting to see, the Bt21 is appearing finally. I was able to help gearbest get set up to carry the light.

Nitefighter BT21 1800LM Cree XM L2 2 LEDs Water-resistant Mountain Bike Lights-15.46 and Free Shipping| GearBest.com

NITEFIGHTER?BICYCLE LIGHT

Update: For ease of finding the main information, I am changing this post to cover initial testing and impressions of the light (plenty of pics!!!)

And time to start the review. DHL was kind and came on a holiday to bring me my light!

First up the case. OMG THE CASE!!!! Quality is GREAT. Very solid, well built, TOP NOTCH. And for me, it feeds my need, MY NEED FOR ORANGE!!!:cool:





All kinds of storage space, enough for second light and pack once you remove gigantic charger. ALso a mesh pouch for storing the small stuff (bands, velcro, whatever else you want to put in it, is got a ton of space too)

Next up parts list:

-Light head: Weight 93g (35ish above yinding for reference), Lumens Id say around 1200 on turbo is my "guess" maybe a bit more but optics make it difficult to judge.

-Charger: 2000mA (yeap 2 amp charger) big solid charger with indicator, very nice.

-Battery pack with pouch: Rubber housing around pack, not cheap thin stuff either. Pouch is dual strap long center velcro tabs to hold pack inside with proper eyelet hole for cable. Uses the nice thick magicshine (available at DX too) 20awg cable. IS true to Capacity (giving margin of error)

-Extension cable, also 20awg MS/DX cable!

-ACTUAL USABLE HELMET MOUNT. Has the rubber type foam on the back, uses 2 long velcro straps for easy use on vented helmets (very excited because sons helmet cant fit an adhesive gopro mount not can my commuting helmet)

-rolled up velcro cable strap (yeap they thought of holding the cables to the frame too, got you covered)

-And Finally, UNDERSTANDABLE and very clear instructions with charts .

Nitefighter thought this one out heavily and I swear spent time reading these forums and learning what we all need. Too bad BT40S kits dont come with all these goodies too.



And WHAT YOU ALL HAVE BEEN WAITING FOR. My "Lab tests" https://ficdn.mtbr.com/images/icons/icon14.png

First up tear down:

Single plate for emitters, can tell by looking at phosphor that these arent 3c, but honestly im kind of liking 4C, think my "winter lights" will be this tint.



This part bummed me out, and DO NOT FOR THE LOVE OF ANYTHING, REMOVE THE SILICONE BUTTON.....Dont ask why I know that, but that shiny center ring around the silicone button is pressed in, holds the button, you arent getting that ring out or getting that button back in... but the driver mounting. 2 screws that sit being the emitters, have a layer of silicone to insulate driver from emitter board contact (if you get brave and try to remove driver which I advise against, make sure to put a new layer of silicone on). Remove the screws, driver doesnt move.....its siliconed in! but no reason to mess with it anyway. Youll see why below.



Also, CAN FIT LEDDNA/GLOWWORM OPTICS, but requires different much thinner oring. Carclo seem to fit right in. OR unless you like to ride in heavy downpours, just take the orings out and put the LEDDNA optics in. they fit TIGHT into face plate so small light rain wont bother it.

Why you can just not even open the light unless you want to change tint or optics:





Ya thats only high not even turbo.

Heres my video review:



You can find more in depth details of these tests starting on page 8 of this thread.

Summary: LOVE THIS LIGHT, turbo gets HOT!!! but except for guys that really get some speed going, turbo is overkill anyway (heat causes it to not push maximum output for long). Everything it comes with OH YA, WORTH THE MONEY!!!

No im not excited at all. :aureola:
 
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#127 ·
Nothing out of the ordinary there

http://budgetlightforum.com/node/11772

Correct me if I wrong, but cells (2 vs 4 cells 8.4v pack) will not change that voltage drop under load. A second pair parallel simply doubles the time it takes for the cells to discharge. Thus prolonging discharge curve.

I have ran my 2.4-2.5A actual (not calculated) in my fenix with keeppower ncr18650b and no issues. Same with my mj880 clone than I have running at 2.9-3.0A. I have less run time at 3A vs 2.5A but on a fresh charge 2 vs 4 cell pack there is no difference visually between either light visually and measured light the little variation can be in my ghetto set up since I dont have a sphere and use my phone app.
 
#131 ·
Correct me if I wrong, but cells (2 vs 4 cells 8.4v pack) will not change that voltage drop under load. A second pair parallel simply doubles the time it takes for the cells to discharge. Thus prolonging discharge curve.
You are wrong. Forget for a moment we have cells in series. It is not important for our case, we need to look just cells in parallel.
Compare voltage curves at 1A and 2A. This is same as running 2 cells in parallel and 1 single cell at same load. In parallel setup load is shared and voltage drop is smaller.

If battery pack is under 2A load and we have single cell it is (obviously) under 2A load. If we use 2 cells in parallel then each cell has load of 1A and thus lover voltage drop. I hope you got it.
 
#128 ·
Last night I ran a test using about 8 different battery setups on my Olympia which is rated for a 2.12 amp draw at 8.4 v and found that the 2 cell suffered significantly more than the 4 and 6 cell packs. There was almost a full volt variance actually between the 2 cells and 4 cells using the same cells. The difference between 4 and 6 cell was much smaller, presumably because I wasn't really drawing enough current for it to matter
 
#129 ·
This is where Archie and vanc need to jump in, im still working on wrapping my head around it but understanding I have thus far is this:



Driver style and emitter count play a huge role in this. 2.1A on 3 emitters is different than 2.1A on 2 emitters. 2.1A on 3 emitters is either grossly under driven or more likely series circuit for emitters. Which means driver has to boost voltage right away.



There is alot more to it than just voltage drop vs current draw. 2 cells run a yinding just fine but same cells on a bt40 or ssx3 is a whole different thing. More emitters require more power to run so going to pull harder on the packs.



And the whole "watts" thing im working on understanding but starting to see why running comparisons need calculations done using watts. Like emitters are rated with lumens per watt.
 
#130 ·
Yeah its difficult to understand exactly what is causing what. It appears that the setups that are series wired are the ones most susceptible to this though. Fwiw i know that the voltage indicator is in no way a accurate way of determining the state of the battery but I can use a light drawing say, 2.1 amps that has 2 emitters and it'll remain green, but on 3 and 4 emitter lights it will go straight to blinking red. It also appears that all the drivers are boosting accordingly and drawing more amperage as the volts drop so I doubt that the output would be affected much either way until the voltage really drops low. I'm curious if this nitefighter has a low voltage protection on the light head itself and what it is set to. If it does, a decent alternative may be to use 4.35v cells or high drain cells instead of my protected ncr18650b
 
#132 ·
Ledoman, does that mean that if it is a higher power lamp, it would be preferable to use a pack with say 6x2200 mah cells that 4x3400s, correct? That may be the reason that gloworm uses a 6 cell pack to make the same capacity in the Xs, vs the 4 cell in others

Edit, I read the comparison chart wrong. The mj880 came with the 6 cell, not the gloworm

Either way, for higher power lights more cells trumps trumps higher capacity cells, correct?
 
#133 ·
More cells you put in parallel more mAh you get and load is shared to the more cells. So you put less stress (load) to each cell which results in smaller voltage drop (hence higher voltage curve).

Higher voltage is important only in some cases. For example if you have higher resistance in wires, connectors, drivers resulting in bigger voltage drop then you very quickly run into situation when voltage drops below leds Vf and led starts dimming or you prematurely get red status light. There are other situation too. Regulated drivers and many leds, etc....

manbeer, yes for more powerful lights tipicaly more cells in parallel is better. You get more mAh and less voltage drop. A rule of tumb would be 1 pair of cells (in series) for one XM-L led. This would give you high output and long enough run time.
So for 2 leds 2S2P pack is optimum by my opinion. Of course I'm counting on cells with 2600mAh and more.
 
#137 ·
This part I knew lol.

Im just seriously deciding if 6cell pack is worth the hassle beyond use on my ssx3 and bt40. Bt40 would be a big help if your running high/turbo all the time. Ssx3 same thing, at least for me and my gotta crank the driver up obsession.

But because of all this discussion (which somehow managing to stay half on topic lol) I ordered new toy for the testing set up, digital volt ampere readout (like what ledoman has). Will be mounted in with my air flow generator so I can do all at once.
 
#138 ·
Hi, received BT21 from ebay auction listing in the last couple of days. Did anyone else's come with frosted lenses?
As it happens the front bolts on mine look like they've lost their hex shaping in over-tightening during construction, the recess looks round rather than angular.
Is everyone else's in perfect condition?
I've just posted on the BT40S review thread that I'd tested current draw and wattage on the BT40s and BT21.
The BT21 looks like it pulls 2.4A-2.5A and is around 20w in the process (on highest mode).
 
#141 ·
dmc71 - I recently received mine. My also has frosted lenses. They look like carclo lenses. My hex bolts look rounded but I have put a 2.5mm hex key in and definitely feel an edge and a fit! I haven't tried loosening the bolt though as I am not known for having the best manual dexterity and would probably end up damaging something anyway!
 
#142 ·
dmc71 - I recently received mine. My also has frosted lenses. They look like carclo lenses. My hex bolts look rounded but I have put a 2.5mm hex key in and definitely feel an edge and a fit! I haven't tried loosening the bolt though as I am not known for having the best manual dexterity and would probably end up damaging something anyway!
Crap. I just ordered one last week. I really don't want frosted lenses but it does depend on the degree of frosting I suppose. As long as the frosting doesn't kill the throw it should be okay but if not perhaps other more clearer lenses can be bought. I want mine for helmet duty.

If any one can provide a ( real ) photo of the front of the lamp that would be great.
 
#145 ·
Okay, the photo helps. These optics look like the standard Gloworm flood optics. I wouldn't call them "frosted" but rather "clouded". Regardless I'm going to expect a beam pattern with limited throw. I do have optics I could play around with, namely the optics in the KD2 duo-clone and my Gloworms. If someone knows the size perhaps I could order some in advance and have them ready if needed.
 
#146 ·
Anyone here who already got their hands on the BT21 managed to get off the face plate? Curious because this lamp seems like an even better host for my DIY reflecting shield, due to the wider area in front and possibly better thermal management. Think it might be possible to hide most of the lower sandwiched material behind the plate on the BT21 whereas the Yinding is kinda skimpy there so most of the anchoring sheet metal has to stick out in an unsightly mess. Also hoping the separation between lenses means I could cut two separate holes rather than a single oval, so there would be a mullion down the middle for extra support.

Tear down eagerly anticipated!
 
#149 ·
It it is like BT40S (they could basically use the same electronic just shaped to fit different housing) it will be VERY hard to notice any PWM. Personally, I don't see any flickering on BT40S in any mode, but then, I am not sensitive to PWM if it's not extremely pronounced.
 
#152 ·
Im not sensitive to it but I notice it on my test set up. Some bad, some not. Bad ones make the fans look like their going backward.

But out riding, ive been out in high humidity and light fog, no issues visually, but my lights also sit centered (extension to put light ahead of bars and centered) which blocks most of tire view.
 
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