2 batteries

[daily double]

If I hook 2 12v batteries pos to pos and neg to neg I still will have 12 volts won't I ??

[rapidrobert]

Yes

[8.1al]

That's right. The wires going to the trailer should have negative coming off one battery and positive off the other

[Bigboomer]

Yes, that is parallel. The volts stay the same and the you will double the amps with 2 batteries, i.e., 2 @ 12 volts/ 200 amps will now equal 12 volts/ 400 amps.

Same volts longer usage.

If you had 2 - 6 volt batteries you would wire in series to double the volts and keep the amps the same.

[daily double]

Thanks I thought I would but wanted to be sure!

[DQDick]

It's worth doing if you boondock at all.