So I tried running it for half an hour and after 10-15 minutes the voltage regulator turned off..... Now I`m thinking of getting this voltage regulator
http://www.robotshop.com/dimension-engineering-de-swadj.html
("Output voltage adjusted via a small potentiometer (1.25 to 13V), 1.5A")
It's little pricey, but it comes with capacitors and heat sink so I don't have to bother assembling them and I can use it for other projects as it's adjustable.
Can it help in my case ?
Thanks!