Thanks Acetronics for pointing that chip to me. It is very usefull in battery supplied circuit. I will order my self a few pieces to test with.

Now i'm stuck at a different problem.

I was using the PWM interrupt routine from Curtis Parrott, which he published here, to drive the Mosfet (the load needs 4Amps at 1.3Volts). http://www.picbasic.org/forum/showthread.php?t=5316

When I raise the voltage to 2.6V the mosfet starts heating very quickly. I don't know where the problem is. Am I using to high frequency?