I am building a layout using EZ Track.  I can't determine how many feet of track I can go before I need another power hookup.  Do I need to solder the tracks together? 

I just bought a bunch of Bachmann stuff to start my layout.  I set up an oval with a couple of EZ-Command turnouts to figure thngs out.  I have the Dynamis system, 4 GP-35 Loco's, a SW1 switcher and some rolling stock.  I am using EZ Track.  When the train is going fast (3/4 throttle or more) around the layout the train works fine and runs continuously.  When Slow it down below 3/4 throttle it will stop in random places.  Sometimes over a turnout, sometimes in a curve, etc.  The slower I go the worse it gets.  My oval only has 18" of straits on each side, so its a small oval.  Is this to be expected or is it something I can troubleshoot and fix?