Plug another switch into an open channel on the reciever just like you did on the first battery. That's it. If you do not have an open channel slot, put the battery and switch on a Y with a servo on a channel. Do not but both batteries in a Y on the battery input of the receiver, If the Y fails, your really hosed.

Hope this helps.

Here is a pic of what I typically do when running a Duralite setup.



Jason