Switching Batteries/series to parallel

I have 2-6volt batteries that need to run parallel 6 volt and be triggered to run 12v series. Does any one know of a way to wire relays to acheive this output.  At rest the batteries need to show 6v and when triggered the batteries need to show 12v. (parallel / series)  thanks in advance.  Jason

Thanks, for the reply,

The batteries I am trying to wire series/parallel are 2 pairs of 6v 12ah Unsure of the current or draw on the circuit.

This is for a "turbo boost" button on my daughter's powerwheels quad runner.  the quad is designed to run 12v but i have succesfully ran her quad with 24v w/o problem,  I tend to overkill wiring and connectors so i think that has helped.

At 24v the quad runs in the 10-12 mph and is a lot more fun for her.

She just cannot controll the quad and manuver it at slow speeds due to the ON/OFF switch, there is no variable.

The reason I want to wire seris/parallel is so when she is off the "turbo" then the quad will draw 12v from all the batteries the same, but when the button is pushed then 24v is switched  with the same batteries. (draw from all the batteries the same again)

Hope this helps explain a bit more.

PS. I have basic wiring skills and can figure out schematics and wiring diagrams pretty well. 

Jason

Thanks that's what I was looking for.  I'll let you know how it goes.  Jason