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[The_Almighty_Bacon_Lord]

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[michaeliv]

Hello,

Welcome to the forum!
Probably the easiest way is to connect the batteries to a constant current boost converter and connect the LED to the output of the boost converter. Done !
http://www.ebay.com/itm/L-/371279559525
Of course if you want you can build the boost converter yourself.
Also, instead of buying those Li-Ion cells directly, buy a laptop battery and get the cells from there, It will be 3-4x times cheaper than the cells you have there + you will probably get higher quality cells.
Ex: http://www.ebay.com/itm/-/281925727410   But there are MANY to be found

Also there's a motor in your schematic, what is that all about.

Best

[mariush]

You need a LED DRIVER, not a regulator. 

You configure the maximum current, for example 0.9A, and the led driver will take the input voltage and raises the output voltage from nothing up to the point where 0.9 amps go through the led... the output voltage could be anything between 9 and 12v in the case of your led. As the led heats up, its forward voltage will decrease a bit (most likely) and the led driver will sense that and make sure no more than the current limit you configured will flow through the led.

If your led has a forward voltage higher than the battery's voltage, search eBay for "boost led driver" or "step-up led driver".
If you can be sure the battery voltage will always be higher than the led foward voltage, then you need a "buck led driver" or "step-down led driver"
There are some led drivers that can work in both modes, they're usually called "SEPIC" led drivers and they're more complex so maybe a bit more expensive.

Here's a cheap boost led driver, works from 3.6v and up and you can configure up to 1A by replacing the two resistors (which by default configure the boost driver to 650mA) : http://www.ebay.com/itm/3-7V-Lithium-Li-ion-18650-Battery-Stepup-Constant-Current-LED-Driver-Boost-Board-/141739123771?hash=item21004f643b:g:GGAAAOSwPhdVLdYr
Here's a very cheak buck regulator that can also be used as a led driver : http://www.ebay.com/itm/Lithium-Charger-5A-CV-CC-Buck-Step-Down-Power-Supply-Module-LED-Driver-/272037297882?hash=item3f56afbeda:g:vesAAOSwo0JWOysB
Set  the output voltage below 9v and rotate the max current almost all the way down, then connect the led and put a multimeter in series with the led. configured to measure current. Now slowly increase the voltage up to 9-12v (you should see the led light up even with 1-10mA going through it) and when you find the minimum voltage, start increasing the current to the point where you're comfortable (900mA would probably be your case). You can lower the current and increase voltage a bit, basically play around with those potentiometers until you find the perfect spot.
Note that a 10w led would have to be screwed onto a heatsink and you may even need a fan to blow of the heatsink to keep it cool.

[Oskar]

The following might be helpful:
http://hackaday.com/2015/05/21/build-a-100w-led-flashlight/

Oskar

[mmagin]

My experience with random no-name Chinese LED modules so far is that their rated current is often the damage level, with no safety margin.  I'd really recommend working with some name brand (Cree, Bridgelux, etc.) module from a regular electronics supplier if you want to make things easy.  Also the good parts have much better efficacy and CRI.