I want to install a 3rd Battery for camping use/ inverter. Since our CTD has a parallel installation under the hood that seems like it could be a problem. Has anyone else done this and if so, how did you decide to handle the wiring for the isolator?

 

Best bet would be a marine isolator.

Mount the spare battery to a frame rail, run the wires and you'd be all set.

As long as you keep it parallel, you shouldn'thave any issues.

Just make sure that it's the same type of battery as the other 2 in the truck, otherwise the weakest battery will draw off of the other two when they are being used / connected together.

 

Are you suggesting running all the 3 batteries in parallel?

 

You'd have to in order to charge it, unless the isolator has a dedicated splitter to it.

Most of them are Bat 1, Bat 2, Both or Off.

Usually Bat 1 is your starting battery(s), Bat 2 is the trolling motor, Both is to charge and Off is self explanitory.

The only thing running them all together is gonna do is increase your available amperage. It's not gonna increase voltage (which would be bad), all it's gonna do is spread the load across more batteries.

Just make sure it's not in series or you'll fry your eletronics.

I would seriously check with a local marina, if you have one. This is a pretty common setup on boats.

 

wiring in series will increase voltage and maintain amperage, run in paralell will increase amperage and maintain voltage.

 

Here is more what I had in mind. The isolator which is normally meant for a dual battery setup, 1 output of the isolator would feed the parallel current setup, the other isolator output would feed the 3rd battery. The 3rd battery could run all the way dead without affecting the ability to start the truck:

 

looks like a winner. just make sure you get an isolator that can handle all that power.

 

You can check with a RV supply place that also services them. Motor homes have several batteries that can be used in several differnet ways. They should be able to guide you on the setup and what is the best equipment for your application. They will not be the cheapest place to buy the equipment but if you ask the right questions you should be able to formulate a good plan then shop for the right price.

 

Just think it through carefully, since there is really more going on than just charging and discharging of batteries when we start our engines on cold morning.

When it is cold and the grid heater kicks on to the tune of 1500 amps (I think) and the alternator cuts out.Will the isolator handle this?

Also, think this through how it might effect your auxilary battery load with the alternator does this. (Will the aux battery be 100% isolated and no back-flow through the isolator on cold morning starts?)

I suggest to check with the manufacturer. Surely, someone has a diesel there.

 

JC Whitney has triple battery isolators for up to 200 amp alternators.