Wiring a battery into a horse trailer

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Hi Folks,

A few questions about wiring a 12v car battery into my existing horse trailer. I want the lights in the tack room and in the trailer area to work when I am not plugged into the truck, so I figured I'd add an aux battery in the horse trailer to do this. I also want to add a couple of exterior lights as well.

I want the battery to charge off the truck when they are hooked up and pulling down the road as well. I'm guessing just hooking the hot wire and ground up to the battery correctly will take care of this.

However, when I turn the truck off, but still plugged into the trailer, what prevents the trailer battery from energizing the truck system backwards? Is there some sort of switch that can be installed in line there?


Thanks guys,
jon

 

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You need to install a battery Isolator in the charge line to the battery in the trailer. The isolator will allow the trailer battery to charge while engine is running but will prevent the trailer system from draining the truck bat. when engine is not in operation.

[This message has been edited by abledog (edited 09-13-2000). ]

[This message has been edited by abledog (edited 09-13-2000). ]

 

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I agree, the isolator is the best bet, also make sure not to use a automotive type battery, a 12v wet cell RV/marine deep cycle will be best for this application. I would recomend putting the isolator in line with the battery installed on the trailer instead of at the truck so you can use it with multiple tow vehicles however if it is only used with your truck then install it on the truck so you can use multiple trailers with aux. batteries. Also something else to consider would be a H. D. relay on this line that is applied power when the ignition is on, otherwise you would have the chance of draining the trucks battery in charging the trailer battery.

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2000 32' Aljo Triple Slide 5th Wheel.

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Add on's to come: Exhaust Brake, Power Edge Box, B. K. 's TC and Valve body,and any other Ram Runner required modification...

 

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Need to be smart in how you do this. You can connect the trailer battery to the truck battery with diode on positive lead and this will prevent draining trailer battery to truck, but would allow truck battery to drain to trailer.

An isolater (basically diodes to both battery banks) normally is installed between the alternator and the battery banks, one bank being the truck's and the other the trailer's. This should work best, and is commonly done on dual battery yacht applications. The isolator allows alternator current to flow to either or both batteries, but prevents current flow between the batteries. Note that your lead to the trailer battery has to be sized according to the alternator output capacity, plus allowance for voltage drop due to distance back to the trailer battery. This will be a large wire (same or larger than lead off of the alternator).

Note that it is possible that a battery isolator may screw up the truck's battery monitoring and/or voltage regulation. Need to look carfully at alternator wiring and isolator unit wiring. One possible problem is that altenator won't charge the trailer battery because the voltage sensed in the truck battery is high enough to limit the alternator output. Some isolators include smart sensing where the lowest voltage of the two batteries is used as feedback to the voltage regulator, which solves this problem.

Its mostly a matter of getting the right type of battery isolator for the application and installing it correctly. Lots of ways to screw up.

 

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Might find this page interesting re isolators. I don't have one. But later will.
http://www.hellroaring.com/