burlesot

Hello,
I apologize for posting a question right off the bat, but I need some help. I am planning to install an isolation solenoid on my 2013 Honda Civic Sedan. The reason for the solenoid is to allow me to charge the battery on my teardrop trailer that I will be towing with my Civic. It is quite light, under 1,000 pounds, but the battery on the trailer will be worn down from use while camping. I would like the battery isolator installed so that when I turn off the tow vehicle, it disconnects from the trailer battery. This will ensure that both batteries do not wear down.

I'm looking for advice on how to know which wire to connect to the solenoid. here is a diagram of the solenoid: http://www.etrailer.com/question-64598.html

I am unsure of which wire to install from the ignition. If anyone can share a diagram or, more helpful would be a photo, I would be very grateful.

Many thanks in advance!

Todd