halogen 6v 100w maglite mod

[Jonaz]

Hi, I am new here.
I won a broken 4D magi-lightlaughinglaughing. It just needed a new lamp. I found for sale real cheap here a new halogen 6v 100w H3
And i saw this
http://www.candlepowerforums.com/vb/showthread.php?t=211991
So I decided to do a similar thing

I think that I should replace the battery, Because the 4D battery make it shine like a 3w lamp.

Yes I know that is nonsense and insane 100w. I need to change the switch, the plastic reflector but first I need to find a compatible battery.

What battery should I use?

Thanks