LED desktop thingy!

I bought a china made LED torch cum table lamp. Costed very less.
Charges well gives 8Hour backup minimum(did not check when it goes off) from a 6hour charge

What is special here is it is a torch with a flip 6ultrabright LED panel.The panel tilts at 15degrees , so you can point the LED sets all directions... that is too much the price of 1 cup coffee in some places .Panel can be hidden when used as torch.
But there is a problem!

The table light /torch loses the intensity after 3hours to 60%.
There must be a way to keep intensity same. I needed a constant current source at least 0.5A.


I searched on net and got (LED driver) : http://www.candlepowerforums.com/vb/showthread.php?t=236260
image:
And I know about joule thief circuit ->simple 1 or 2 transistor circuit increases the voltage.
Here is joule thief:

(i assume battery is 6v )
Plan is :
battery(6v)>joule thief(9v)>LED driver>LEDs

smooth white light till battery loses the charge (if backup become 6Hrs , fine na!)

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