Got to thinking, and came up with a question.

[Casper]

I have been getting ready for a 3 week trip over the last few days. As I was going over everything in the trailer and truck I decided to turn the fridge on in the trailer to cool it down. This got me thinking. I have a battery in the trailer, and the plug for the trailer plugged into the truck. If the fridge drains the trailer battery, will it drain the truck battery as well?(when the truck is off of course) If the answer is yes, is there anything I can do to stop it? Put a one way valve type thing on that would allow the truck to charge the battery and not drain the truck? I will be adding a 2nd battery to the truck some time soon, so it could be part of that system as well. Just wondering.

Thanks

Casper
:safari-rig:

 

[4RunAmok]

YES! Put one of these, truck-side, on the power + and - of the cable that runs to the trailer.
http://www.powerwerx.com/product.asp?ProdID=34689&CtgID=1896

 

[ntsqd]

Some other options:

Surepower Separator

Blue Seas Automatic Charge Relay

Constant Duty Solenoid

(Note: I'm not promoting West Marine as a vendor, just pointing the options available & using their pages for help in doing so.)

 

[TheRoadie]

The Powerwerx is a cool gadget, and I'd use it for radio loads, etc. But in this case, the vehicle to trailer wire also charges the trailer battery. If the fridge totally drains the trailer battery, the Powerwerx relay will be open. When the vehicle starts, the relay closes and the inrush current to charge the trailer battery is limited only by the resistance of the wiring. If it's more than 20 Amps switched (the Powerwerx rating) there may be some damage (relay might weld closed). Just my worry as an engineer.

 

[Mike S]

A simpler idea...

Set up a relay on the power feed from your battery to the trailer connector - near the battery. Control the relay with keyed power. This allows the trailer to receive power only when the vehicle is keyed ON. What size wire do you have for the trailer power feed?

The power separators will work, but seem to be an unnecessary expense to solve this simple problem.

If you need more battery - add it to the trailer. You could also add a charger - controller to the trailer.

Mike

 

[Martyn]

Casper

The simplest solution is to unplug the trailer from the vehicle when you are in camp.

Most vehicles have 10 gauge wire back to the 12 volt on the socket. The trailer has 10 gauge to the deep cycle battery.

 

[4RunAmok]

The Powerwerx is a cool gadget, and I'd use it for radio loads, etc. But in this case, the vehicle to trailer wire also charges the trailer battery. If the fridge totally drains the trailer battery, the Powerwerx relay will be open. When the vehicle starts, the relay closes and the inrush current to charge the trailer battery is limited only by the resistance of the wiring. If it's more than 20 Amps switched (the Powerwerx rating) there may be some damage (relay might weld closed). Just my worry as an engineer.

You could use the unit to control a continuous duty solenoid since it works on voltage readings and not loads.

 

[spressomon]

Casper

The simplest solution is to unplug the trailer from the vehicle when you are in camp.

Most vehicles have 10 gauge wire back to the 12 volt on the socket. The trailer has 10 gauge to the deep cycle battery.

This is what I do...has worked fine for the past 18+ months. Nothing fancy...just works.