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That's mad... How can that be 5000 lumens?

The max 2 * XML U2 can pump out is just over 2000 lumens

That's the one. Although that listing is way over the top for lumens output. a single XML U2 cannot output 2500 lumens even if overvolted so 5000 lumens is just a lie.
It's more like 2000 lumens with both LED's on full. See: http://www.lightmalls.com/red-color-sol ... 50-battery

Edit: all say at once, no way 5000 lumens!

I have just spotted same light but 3x XML U2 LEDs. I am after a good bar "flood light" for 2 hour rides. With all these claims of lumens I could see me borrowing a lux meter.

How do I work out battery life from stats, Maths possible ?
Run Time At Least 4 Hours On High Mode, also has Digital Current output cooling of light.

8.4V 6600mAh 6x18650 Battery Battery Pack
LED 4xCree XM-L T6

My MagicShine MJ-808 battery had a good 3+ hours but not holding much charge now.

A rough guide would be:

battery capacity in mAh divided by load current in mAh.

So for your example:

An XM-L T6 has a maximum drive current of 3A or 3000mAh, therefore if you were running 1 XM-L T6 to the max you would get: 6600/3000 = 2.2 hours or 2 hours 2 minutes.
Multiply that be 4 and you get 0.55 hours or 33 minutes and your headlamp housing would probably be melting.

However, it's not that simple. The driver in your light (the PCB circuit), dictates the current draw and this component will be match with the number of LEDs, how well heat is dissipated and a target run time and light output.

So for example, a typical 4 x XM-L T6 might output 3000 Lumens. Cree rate the LED's at 1040 lm @ 10 W. At 3000lm each LED would be outputting 750lm and therefore drawing 7.211 W (10 W / 1040 = 0.0010 W a lumen X 750).
Still following? 7.211W x 4 = 28.85 W. Convert this to Amps (power in Watts/ divided by supply voltage), 28.85/8.4 = 3.43 A, stick that in the original calculation: 6600/3430 = 1.92 hours or 1 hour 55 minutes and 12 seconds.

Runtime will always be less than this. Things such as cable length, ambient temperature, day of the week etc will all play a part to reduce it.

Nice overview Eccles!

I have gotten my hands on a 6*XM-L2 U2. It offers a massive flood. Managed to get 3 hours out of a 6x 18650 cells 6600mAh battery in testing which is about twice as much as I hoped, even though it offers better efficiency than the XM-L's Nice

Ok so I've been back to the light malls site and can find no suggested day of week variable but I can tell you that they are drop shippers so I'll avoid them at all costs i think, especially for popularitems where they'll delay orderinguntil they get a specific number of orders so they get further discount and you get delay. Got that not from the site but from work

I raise your 5000 & give you 6000 mwahahaha
http://r.ebay.com/9Vscpy

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My light turned up today, tidy little thing, nice and small and very light, good connection. Looking forward to getting out with it now

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What!!!!

You still not got yours?

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Nope!!!

Finally arrived......... And one of them has a bloody cracked lens!!! FFS!!!

I played around with my lights last night, the new one works really well, brighter than my Majicshine MJ808 so thats now on my bars.
I'd taken the micky mouse shaped one off but had to replace it as the megga 3 x T6 one is now not working at all? the battery works ok, but nothing from the light it self?
Need to get it checked out? Now if only i knew a bloke who likes to take apart lights?