Dual Trailer Batteries wiring Question

[Rezarf <><]

Hey guys, I searched but I am trying to get an answer to just one question in particular... I didn't do so hot in my Electromagnetism Physics in College.

Here is my setup:

2 12v batteries
An on board 2 bank charger

My question is, how do I wire the batteries together to keep the voltage at 12v's verses combining them and ending up with 24v?

Series or Parallel?

So is it:

+ to +
- to -

Or do I wire the posts:

+ to -
+ to -

Thanks! I appreciate it!

Rezarf <><

 

[HenryJ]

Parallel + to + and - to - is 12 volts.

 

[Tucson T4R]

X2 + to + and - to -

Here's a pic of my dual battery set up in my trailer. The negative terminals are in the fron and the positive are in the rear.

 

[Rezarf <><]

Thank you kindly fellas!

:victory: