Dual Battery set up... AND trailer battery... How to configure?

[nater]

I have searched and searched, and have not come up with a solution to my question. I am going to install a dual battery system in my FJ (assembling parts now), and I have recently acquired a teardrop that charges its battery off the 7 pin connector. Does anyone have any recommendations on how to set up this charging system with 3 batteries? I dont want the trailer battery pulling down either my aux battery, or main battery over night (lights, tv, fan, etc), but I want it to charge while I am driving.

Thanks guys!

 

[LandCruiserPhil]

The simple fool proof way - Install a relay on the 12v trailer charge feed to activate (make) only when the vehicle is in the running on position.

 

[AndrewP]

Agree-Feed the trailer +12volts with a continuous duty 100 amp (roughly) relay. Set the relay up so that it combines when the truck is running and opens, when you shut the truck off.

The slick (but more spendy) way would be to feed the trailer with a voltage sensing relay (aka ACR = Automatic charging relay).

In fact, you could use 2 voltage sensing relays and make them the same for ease of install and redundancy. Use one to feed your second battery and the other to feed your trailer. That would be easy to install and nice.

It goes without saying that you'll need to fuse your cabling for safety at each battery.

 

[nater]

So, for various reasons, I was considering the CTEK Dual 250S to charge my trailer.

Could I place the CTEK Dual 250S on the trailer, wire it to my 7 pin and trailer solar, and allow it to take care of the battery on the trailer that way?

Any ideas of how it would interact with a ACR in my truck?

Just making sure I have my ducks in a row!

Thanks!

 

[Terawanderer]

I've had the 250 for about two years now......using two 60 watt panels.....and have all the power I can use. You won't be sorry if you get one. It was recommended to me by Teotwaki.....he knows his stuff !!