thanks i will do that... the cars i have now have batteries for the interior lighting

So i just bought this set...its the Bachmann Liberty Bell set, everything looks good I see that i may have some minor poor connections on the track itself however when i run the locomotive by itself it runs ok..not fast but ok...when i add the passsenger car it bogs down even when the control is all the way up.  I did also read that the control (standard that comes in the box) may be low voltage as well and most people up for a better control system.  This is our first set and we want this to be an ongoing outdoor project...

Any suggestions?
Do i need a bigger power supply?
is the locomotive poor?
New Drive?

help..
thanks!