Brontelight BT31 Super Thrower review

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Bc412
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Brontelight BT31 Super Thrower review

Note – I received this light from Brontelight in exchange for the review. This light is currently not available for sale at the time I’m writing this, but will be soon. The light I received for review was described as an “engineering prototype”. As such, it did come in used condition.

I’m going to be adding more to this posting as I got along. I’m going to add more white wall shots of the beam, and also try to do a full tear down. I was reluctant to tear it apart before I fully completed my review.

factory Specs:

BRONTE BT31 Low -50lm 45 hours Medium -1500lm 1.8 hours High -2000 lumen 1.6hours Strobe (9HZ)-2000lumen

1420M Beam Throw 500000cd Cree XHP-35HI 4×18650 IPX8 (waterproof up to 2 meters) 1.5M shock 210mm 993g 96mm

Performance:

This was a tough light to do testing on because of how extreme that hot spot is. So my brightness charts were done using the ceiling bounce method in order to eliminate any problems with the hot spot overwhelming the senor.

So we ended up with a total runtime of 120 minutes plus change. We keep above 50% of original brightness for 110 of those minutes, which exceeds the 96 minutes that Brontelight advertised by almost 14 minutes. I tested using 4xNCR18650B batteries.

I ran the runtime using the ceiling bounce. I could not measure the beam directly at room lengths, it was too intense for my lux meter at such short distances. I tested all 4 batteries upon removal and found them to be: 3.06 3.29 3.31 3.50V So I think it is safe to say that this light has LVP. Also seeing that the voltages went up as I tested, I’m assuming that is just from the batteries being able to rest a few second longer than the first I tested.
There is no step down of power with this light, and the light shut off with no warning whatsoever. It did dim dramatically in the last few minutes, so there really isn’t any chance of over discharging the batteries unknowingly.

I put this light up against the Thrunite Catapult V5, Convoy C8 (xml-2), Olight R50 Seeker, and the Klarus Xtq2 to see how efficient the light really was, and also some comparison of the mode brightnesses. I plan to add some additional flashlights as time goes on.

Also to note during my runtime testing that the flashlight never got too hot too handle. It did get warm, but never enough to make it uncomfortable to pick up. Heat dissipation is good. However, I will not that I could hear the glass lens pang a few times as it warmed up during testing. Could that be a problem? I’m assuming it is just from thermal expansion.

From what Brontelight tells me the batteries are set up in 4S so I’m assuming that means the XHP35 is a 12v led.

Construction:

















Bear in mind this light was an engineering prototype and was used when I received it. It had quite a few dings in the anodizing when it arrived. The reflector looked to be in great shape for such a big smooth reflector. Didn’t see any flaws worth noting. The threads for the tailcap are not anodized. With a light this size which will likely end up in truck beds and boats, I would like to see the threads anodized for a mechanical lockout of the light. The threads came dirty and were not the smoothest, but this could be a prototype issue rather than a production issue. Hopefully Brontelight takes the time and effort to make great threads on the production model. The light tail stands and is very stable despite the big head. The stainless steel bezel could not be removed by hand. After my review is complete I’m going to do a teardown, but didn’t want to risk hurting anything before my review is complete. The block knurling on the body of the light is good, and is comfortable if you are holding the light from the tube. The handle could use improvement also. I took this thing out trick or treating for a few hours. Firstly the light is very front heavy, so you constantly need to apply pressure to the handle. This does fatigue you quite a bit. I found myself changes hands frequently towards the end. The balance doesn’t let the light just hang from your hand. The handle is also a bit on the small side. The finger grooves did not line up completely with my hands, and definitely wouldn’t if you had gloves on. Both switches are a little mushy as well. I did have several times I hit the switch and it did not change modes. Once again I really hope its a prototype issue and not something that will follow the light into production. The glass is not AR. This is something I would love to see improved on this light as well. The battery carrier seems well built. The screws holding it together are stripped out as you can see from the pictures. It will hold NCR18650B with plenty of room to spare. This will likely not be able to handle the shortest flat top batteries.

Beamshots:

This is a zoomed in picture of a soccer goal at about 500 yards. The beam is still very strong and organized at this point. I have no doubts whatsoever this can hit 1000 yards. The picture does not do any justice to the light, it is of course much brighter and crisper to the naked eye. Having to zoom in really took away from the brightness.

At close distances under 100 yards the beam is overwhelming to try to get a good picture of.


So if your interested in white wall hunting your going to be disappointed. The light has some rings. However the hotspot is clearly focused and very well defined. The spill is also well focused around the edges and is just enough to keep in front of you well lit. When you take this light out at night it truly does give you that light saber effect because the hot spot is so well defined. The temperature is a fairly cool white as well. I didn’t see any traces of blue or green in the beam.

Youtube Review:

User Interface:

This light is simple. It has 2 switches that seem to perform the exact same function. You can operate the light from either switch or a combination of both. A long press turns the light on. Short press cycles between the three modes. Double click while on brings you to strobe. Another long click is needed to turn the light off.

My analysis:

The Good:

This light is a pretty amazing thrower. I don’t own any other throwers of this caliber so it is tough to compare to. My pictures really don’t give this flashlight beam the praise it deserves. You can run this light the entire runtime on high without it overheating or getting too hot to handle. With the multi-switch design you can hold the light via the tube or handle and utilize it. The light tailstands nicely, and the bezel is stainless steel and crenulated. This light held 50% of its original brightness over 110 minutes. That in itself it very impressive. I’m pretty sure with a short rest I could have easily turned the light back on and squeezed out some time on the lower modes after my run. The light is simple to use and seems pretty tough. This prototype had alot of dings, so obviously it saw some rough treatment. The battery carrier doesn’t seem to have polarity, so you can put it in either direction without worry. Otherwise this light put out a great performance in the runtime test, and this could improve possibly with different batteries, or cooling during the test. Reviewing mega-throwers is tough. They aren’t super practical, so the kind of guys who will buy them are flashlight addicts (of course) and people with a distinct need to throw a flashlight beam nearly half a mile.

The Bad:

Don’t consider these bad, but instead things that need improvement. Hopefully Brontelight takes some of this into consideration. However, please bear in mind that some of these criticisms may be because I have a prototype and may not be an issue in the production models. The threads are not the best, and should be anodized for a mechanical lockout. The handle is too small and the balance of the light is all in the front, which means you have to apply pressure to the handle to keep it in your hand. This will wear you down during long use. The glass lens is not AR, and should be. The switches on mine were a little mushy. That could just be from extensive testing, travel, etc… Also there really should be a blink or step down before the light shuts off. Sudden shut off like that can make a bad situation even worse.

Conclusion:

This light is a big heavy beast of a thrower. As we know, it isn’t going to be cheap. Brontelight didn’t want to tell me the MRSP for this light right now, but hopefully they are reasonably with this so it is affordable. This isn’t going to be a light for your average guy walking his dog. This isn’t even going to be a light that would be appropriate for security or law enforcement work. This light would be great for search and rescue work, hunting, and for use on a boat. The XHP35 Hi is a great choice for this light and it really does a good efficient job or putting out alot of lumens for a very long time.
The BT31 doesn’t have all the bells and whistles that the Lumintop SD75 has, and hopefully that reflects in the price. I really enjoyed testing the light and being able to see what Bronte did with this guy. It will definitely be useful to the guy who wants a simple, no frills mega thrower.

suggestions:

Being this light is new, and still not available I wanted to put some suggestions I think would help the light. Firstly, I would love to see a shoulder strap for this light. I think this light needs some kind of attachment point at the tailcap. This is a big heavy light, and I would be reluctant to carry it for search and rescue work if I didn’t have a means to attach to gear, belt, or shoulder strap. At a minimum it needs a lanyard hole. I also would love to see this light shipped with a spare lens. That is one huge glass lens and having to find a replacement would be a nightmare. I also am a firm believer that strobe mode is essentially useless outside of tactical flashlights. I would much rather see a beacon mode with this sort of light. If your going to use a light like this on a boat, or for search and rescue a good long running beacon is a must have. 110 minutes of strobe is great, but I’d rather have 20-30 hours of a beacon for emergency use. Especially if your using this as a truck light! If your car broke down on the road using that strobe would blind other drivers rather than get you help. I’d rather see a slow beacon that will still gain attention without blinding potential rescuers.

Bc412
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Reserved for additional run time tests, and beam pictures.

Rusty Joe
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Thanks for the review. Looks enticing.

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AlexGT
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Thank you for the review, What is the size of the reflector?

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Just me being a broken record again, but imo, skip the blinkies entirely. That was almost a dealbreaker for me even getting my L2, and every time I accidentally double-tap the switch fast enough to kick it into strobe mode, it just plain pisses me off.

Who’d want to have a super-thrower with extremely-narrow-angle beam and use it in sos/beacon mode anyway? You’re shining a batsignal. That’s like putting sos/strobe/beacon on a laser-pointer.

Unno, sounds like a “teats on a bull” situation to me…

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The Miller
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Nice review!
Thanks very good to see what kind of markerbeam (sharpies being bigger then pencil) the XHP35 makes.

djozz
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Very nice review, that is an impressive light, and could be one of the inspirations for the BLF thrower under construction Smile

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Great review, thanks a lot for that!! Thumbs UpThumbs UpThumbs Up
.
An impressive light indeed, however, to be interesting for ME, it should have

  • no rings in the beam
  • excellent heat management
  • be modding friendly
  • have an AR coated lens
  • perfect ano
  • perfect threads
  • ano tailcap threads for lockout
  • a host only version for modding purposes (Oslon Black Flat) Silly

After all, it is not going to be “cheap” (one could endlessly discuss the meaning of this word, let’s not go there) so it should tick MOST of the boxes.
Most wishes are depending on the price level, of course.

My conclusion: good to see yet another manufacturer entering the super thrower range of lights. The more competition, the better.

@ Djoizz: I agree, the design itself could be interesting for the BLF super Thrower project…..

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Rusty Joe
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Can the carry handle come off?

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Bc412
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The Miller wrote:
Nice review! Thanks very good to see what kind of markerbeam (sharpies being bigger then pencil) the XHP35 makes.

I really wish I had another thrower of this type to compare to at that range.

And a better camera that could handle the long distance shots better!

Bc412
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djozz wrote:
Very nice review, that is an impressive light, and could be one of the inspirations for the BLF thrower under construction Smile

I’m going to do a full tear down soon. Then we will know how good a candidate this is.

I’m sure spending some time getting the beam focus perfect, and a fet driver this could get out a few hundred more yards

djburkes
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AlexGT wrote:
Thank you for the review, What is the size of the reflector?

+1 ?

Bc412
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I’ll take a look tonight after work

mdeni
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Make comparison pictures with many lights.

Measure throw kcd.

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mdeni wrote:
Make comparison pictures with many lights.

Measure throw kcd.

Please. And thank you.

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Nice review but I find it strange to review a thrower and no mention of Lux other than a claimed 500k. Is this just the claim as it looks or have I read it wrong or missed something? Question

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The Miller
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nice, turned on the pc to check it for on phone on 3G not doable.
looks good.

Bc412
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Apparently sli.mg is down again. Once it’s back up I’ll port the pictures and charts over to photobucket.

Meanwhile I’ll see if I have the runtime charts at home to repost.

giorgoskok
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Bc412 wrote:
Apparently sli.mg is down again. Once it’s back up I’ll port the pictures and charts over to photobucket.

Meanwhile I’ll see if I have the runtime charts at home to repost.

sli.mg is about 4 months now dead , since i posted this : http://budgetlightforum.com/node/52292

Bc412
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giorgoskok wrote:
Bc412 wrote:
Apparently sli.mg is down again. Once it’s back up I’ll port the pictures and charts over to photobucket.

Meanwhile I’ll see if I have the runtime charts at home to repost.

sli.mg is about 4 months now dead , since i posted this : http://budgetlightforum.com/node/52292

I saw that thread. It did come back up for a bit afterwards and I let it be.

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I sure wish I could get this light. Doesn’t seem to be available anywhere though.

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