wat is a UBEC/BEC?
 

i'm putting a 9xl with a MM esc, and goin to be running 14-16 cells, i was on here before and they said i should use a ubec. I dont know wat this is. O and when wiring up my batteries should i put them in a series or a parallel curcuit?

Welcome to the forums!

This page should help you out.

so if im runnin 14-16 cells with my 9xl do i run a series or parallel for my batteries?

series increases the volts (speed) and parallel increases the battery capacity (run time) im guessiing you will want them in series for the extra volts

ok so if i run my 16 cells in a series wat do u think ill get for top speed? and my motor can handle this?

probably about 45 mph at a guess and yes your motor can handle it but the controller is only rated up to 12 cells all tohug i have heard of people runing them on more.

i am runnin it with a ubec.

4s (16.8v full charge) with the UBEC is no problem for the MM, I have one set up that way. 16 cells would be a bit more initial voltage, but some have had good luck up to 5s (21v full charge) with the MM.