3800 Lumen light , is it safe ?

I have been looking for a powerful bike light/ headlamp to light up the trail as much as possible. I found this 3800 lumen (probably produces less I know, hopefully 2800-3000) Cree XM-L T6 (x3) light for both on bike and on head use :

http://www.amazon.co.uk/dp/B0097A6R2E/

It has good reviews and is sold all over the place to the UK market (from HK and China). However it says nothing about the batteries or charger other than 6000mah. (I have assumed its 4 or 6 18650 cells)

However I have just seen the stories of exploding lights and batteries on this forum. I have also read the forum safety guide.

So the question is how do I know if this is safe? How great is the danger? I don't want it blowing up on my head or in my face (or my friends who also want to buy it).

Safe is obviously a battery question, the light itself however cannot be 3800 lumens, the max lumens rating for those LEDs (each) is 1040 at maximum power, and with optical losses, 2800lm max is reasonable "out the front'.
BUT, that much power (30 watts) in a lighthead that small, is going to run extremely hot at the LEDs, so they are not going to be putting out nearly full output (or the power can't be running at the max 10w/emitter). One way or another, even 2800 isn't likely. Might be a decent light ignoring the specs, but it's claims are untenable.
Regarding the batteries, you have to know the details on them. Nothing in the specs makes much sense, including the lighthead is "steel, anodized" which is not a process you use with steel, so it's either steel parts AND with anodized aluminum parts, or it's all anodized aluminum. If any part of the thermal path is actually steel, it's going to cook the LEDs, steel won't get the heat out fast enough to keep the LEDs cool even if the surface area was great enough (it's not).
Looks to me like it probably has a basic low-voltage cutout board (PCB) on the batteries, but since it doesn't say "charge protection" or anything like that, then the charger could still blow the batteries. There just isnt' enough in the link to tell, but based on all the irregularities, I'd not trust it much without first disassembling all parts (at least the battery pack) and going through it with a fine-toothed comb.
Based on specs, looks like it's charging around 1C rate, likely just a simple "dumb" power transformer/rectifier with some type of either time, or voltage cutoff. For this price, it won't be a high quality, well regulated charging setup for sure. Buyer beware.

the question should be, not if the light is safe, but if batteries you use are safe. use good quality protected cells and you'll be fine.

those lights are bike lights, they can get enough airflow for cooling when are installed on a bike, and bike is in motion. putting that on your head will sure make it overheat, it wont blow up, but it may just expire cooking the leds. or driver. use lights that are designed as a headlight on your head.

you don't see any reputable company build 3000lm headlamp, there is prbly a good reason why they don't.

These types of light use a proprietary battery pack which, from the shape of that one, will have 4x18650 in 2S2P configuration giving 8.4V output. There should be built in balancing and protection with a pack like this even at that price.

The 3800lm output is well overstated and will be theoretical LED lumens. The reality will be much closer to 1000lm, which is still very bright (too bright to use on full in town).

Will it be safe? I would say it will be safe enough, with the only possible danger being if you leave it on charge for a long long time (but even this is minimal). I would not expect any issues during the actual use as the pack is not sealed into a metal tube and should be using protection. (explosions are only really attributed to damaged li-ion cells being fitted into a sealed battery tube) Li-ion safety is often overstated on CPF considering this type of battery is in the laptops, tablets, phones and cameras billions of people use every day.


I've been using lights like this for several years and never had any hint of an issue and I am quite sure Amazon wouldn't want to sell any products with flaming potential (apart from lighters and BBQs and other things that are supposed to catch fire). There are a couple of things to bear in mind that I have found on this type of light:

In all examples I have used, the charger has a charge indication lamp. It shows red when charging and green when charged. If you connect the charger to the battery pack but do not plug it into the mains, the green light shows and like this the charger actually discharges the battery. I found this after using a timer plug to cut off the power to the charger after 8 hours of charging, then forgot about it. I found it a couple of days later and the battery had been fully drained by the charger unit's indicator LED and I had to recharge it (after which it did not appear to have suffered any damage).

The light head will also draw power from the battery even if the main light is not on. If you leave the ligth head connected to the battery pack and then don't use it for a couple of weeks it will most likely have drained the battery, so each time you finish a ride remember to disconnect the battery pack.

Apart from those little 'features' this type of light has a lot to offer.

whitedragon101 said:

I have been looking for a powerful bike light/ headlamp to light up the trail as much as possible. I found this 3800 lumen (probably produces less I know, hopefully 2800-3000) Cree XM-L T6 (x3) light for both on bike and on head use :

http://www.amazon.co.uk/dp/B0097A6R2E/

It has good reviews and is sold all over the place to the UK market (from HK and China). However it says nothing about the batteries or charger other than 6000mah. (I have assumed its 4 or 6 18650 cells)

However I have just seen the stories of exploding lights and batteries on this forum. I have also read the forum safety guide.

So the question is how do I know if this is safe? How great is the danger? I don't want it blowing up on my head or in my face (or my friends who also want to buy it).

Click to expand...

IT can't be 3800 lumen that high, since the max lumen of Cree XM L2 is 1052 lm.