Fake News

[daniela124]

I do not favor censorship, but sometimes one has to put the foot down.

In electronics (which is my thing) there are two lies on which are far too common.

1. A LiIon battery of type 18650 has at the most 3.6A/hr !!! and do not let the label tell you any different.

Actually if the label tells you it has 5A/hr it is a lie and the truth may be around 2.5A/hr.

2. "tactical flashlights"  with 15000 lumens ... sorry hard to believe, because the best LEDs you can buy have an efficiency of 200 lumens per watt. This would mean you take 75W (20A) out of a single 18650 LiIon battery. A more realistic figure would be 1500 lumens which is still incredible bright and will blind you if you look directly into it.

[daniela124]

I want to add a few more facts to my tactical flash light post...

I found one  ($65) which claims 32000 lumens using 21 CREE XM-L-T6 (or 24 it is a bit unclear from the description). Since the item comes from China it uses most likely a knock-off and not a Cree LEDs but even with the benefit of the doubt, it cannot be. The Cree data sheet on the XM-L-T6 LED states that at the maximum current of 3A a single LED has an output of 910 lumens (efficiency 91 lm/W) and I am generous because this will get hot quickly and the efficiency will go down rapidly with heat. If you multiply this by 21 you get 19000 (21800) lumens and NOT 32000.

Please note that the light output is not linear with current.

But even that is all too generous. You are taking 210 watts out of the batteries. You better buy some of these high drain batteries you use for model airplanes...  Anyway at 210W these LEDs get so **bleep** hot  (because they are NOT 100% efficient) that you better use gloves  holding this flash-light.

Yet it is more likely that this is a very bright flashlight with 21 (or24) Chinese made knock-off LEDs which overstates its light output by the factor 10.

And last, the real good Cree XM-L-T6 LEDs cost about $2 a piece in quantities

So, now there will be a lot of replies from people who do not know volt from amperes, who claim that I must purchase such a flash-light before I should have a right to critizise... no... because the claims are beyond any industry standards and therfore false.

KB