Camper trailer charging, not as simple as I thought

[GeoffV]

Hey all

So I got the local Deerings Auto electrics to install a Red Arc Battery isolator in my WK2 with an anderson connection to the trailer. After getting some other electrics done by another installer, I find out that it's no good for this car due to the variable voltage alternator (Deerings didn't realise this either). Red Arc has confirmed this, and they are now doing up a system so I can charge my battery in the trailer with a BCDC1225 in vehicle battery charger/MPPT regulator. Although this is all going to be fitted on the trailer by the looks, because I am going to be putting my solar panel charge through this also. And the plan is going to allow me to back charge the car with the solar panels also. So I'm thinking that perhaps I'm not the only one out there who has had the simple isolator installed. Thoughts or comments welcome.

[scarps]

What year WK2?

I've got a 2012WK2 CRD and have successfully installed a dual battery system with a Piranha isolator and rear 50amp Anderson Plug that I hook my CT into with 2 more batteries on the CT. So all up my alternator charges and maintains 4 Deep Cycle batteries when all hooked together.

[yoda42]

My 2011 has no trouble charging the batteries (2x 100amphour) in our CT through the redarc and anderson plug, and no prob when we throw the car fridge in the back with its 100amphour through another red arc so 3 extra batteries plus the start all charge no problem

[JamesLaugesen]

Originally Posted by GeoffV

Hey all

So I got the local Deerings Auto electrics to install a Red Arc Battery isolator in my WK2 with an anderson connection to the trailer. After getting some other electrics done by another installer, I find out that it's no good for this car due to the variable voltage alternator (Deerings didn't realise this either)..

What size/count wiring (and anderson.) did they use?

[scarps]

Originally Posted by yoda42

My 2011 has no trouble charging the batteries (2x 100amphour) in our CT through the redarc and anderson plug, and no prob when we throw the car fridge in the back with its 100amphour through another red arc so 3 extra batteries plus the start all charge no problem

Think it might be these new fangdangle WK2's with all their 'lectronics and gizmos and stuff lucky we got the older ones........

[fester]

Originally Posted by scarps

Think it might be these new fangdangle WK2's with all their 'lectronics and gizmos and stuff lucky we got the older ones........

It's quite common with many newer vehicles. The alternator is controlled by the ECU and apparently puts out less voltage than we traditionally know. I've read of Pathfinder owners who found the controlling wire and snip it reverting the alternator back to normal change. A mate at work has just bought a 2011 Subaru Forrester and was told his alternator only ever puts out 11-12 volts so he is going the dc/dc charger route also. Not sure if the wife's Mitsubishi Challenger does it as well but I chose to fit the Projector dc/dc charger as it makes the whole instal much neater and simplier. Charger in the van and smaller wiring required to connect to the main battery so easier to run. I can also wire my Jeep the same and simply and we have proper charge management in both cars (we have no real need to run a dual battery in the vehicle these days).

So different hardware, but really still quite simple if not simpler due to the reduced wiring requirement.

[turbomart]

Yep as fester said.
My wj only puts out 13.2volts, bout 13.8v after mod.
If you get say 1v drop from car to trailer then it leaves 12.2 volts to charge , battery full charge volt is 12.6 v so you would be going backwards. Most 12v batteries need approx 1.5 v more input than charged volts to overcome internal resistance.