Truck camper isolation from truck batteries wiring issue

When I recently mounted our truck camper (2003 Bigfoot 1500) I plugged in the 7 pin wiring plug from the camper to the truck bed and started the refrigerator on propane since we were heading out for a little shakedown trip the next day. When I went to start the truck the next day, the truck batteries were dead, reading about 6 v. It seems as though the camper is drawing off of the truck batteries and not using the house batteries.

1. Seems odd that it took less than 24 hours for the truck batteries to die, since I was only running the fridge.

I contacted a mobile RV repair service I've used in the past (mixed results but they're convenient and supposedly very knowledgeable about 12v wiring). They set it up to now be isolated and so that the truck charges the camper batteries via a DC to DC charger. They assured me that the camper will not draw power from the truck batteries.

2. Take a look at the wiring job and tell me if you'd be happy with this. I can't help but think there's a cleaner and more professional looking way to do this.

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There's way better ways to do that! The crimped ground wire will chaff through after the first trip with being pinched under the lid! There are plenty of Ignition hot wire to activate the relay for the charging system. The use of an unsealed butt connector and the electrical tape wrap are a tell tale that there is no pride, just get it done! Very easy to assemble a harness, and mount the relay to a fixed point versus floating around in the fuse box. Hope the bill wasn't to bad. Good luck with the shake down trip.

 

The crimping tool used in your edited photo below is a good crimping tool, but in this case the tool was used in a wrong application. This tool is designed for use with a non-insulated crimp connectors.

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The following photos show what a non-insulated crimp should look like. Note that the seam in the connector is contained in the saddle of the crimping tool.

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The connection should be covered using heat shrink with a sealer.

- John

 

Instead of modification of the truck it would be smarter to modify the Camper that it doesn't pull power from the truck with the engine off..

With the B-2-B charger* that is accomplished as they sense the higher voltage with the Alternator charging and switch off as soon as the engine is off again.

So, the hack in the fuse box is actually useless in my eyes.

*given correctly installed!

 

Thanks for the feedback everyone. I'm now tasked with telling the mobile rv guys the work is of poor quality AND finding someone to redo it all correctly. Not sure where to look for that...

 

I had my camper builder install an isolator. Truck running charges the camper battery but nothing in the camper can drain the two truck battery’s. Going down the road the refer will run on the camper battery and the trucks alternator will charge it. But when you stop you need to switch to propane . Camper refers drain the battery pretty fast. If it’s not too windy I can drive down the road on propane until the pilot like blows. Then there’s 120 v so it’s a three way setup for the refer. Shorepower

 

Use your ice cube tray as your gauge. And always get your refer up to the temp the day before you leave and food also

 

Find a place that builds campers they know how to do it right.

 

Dry Ice is the handy jump start.

 

Why not use the traditional diode pack that isolates the charging system?

 

There is a .6 voltage drop across a diode. Combining that voltage drop with long wiring runs will give poor charging performance for the RV batteries.

- John

 

Shouldn't be used anymore, to many downsides like said.

Superceded by MOSFET technology if someone does not want to use a Relay or a B2B charger.

Something like this > https://www.getlithium.com/29d_Perfect_Switch_Programmable_Autonomous_Relays.html as an example, there are more and other available of these solid state switches.

 

Looks like a roadside repair. Along the Dalton Highway. At Toolik Lake. Don't ask how I know this.

 

So you're saying this device you linked would be used in lieu of a DC to DC charger? I'm currently running two 100ah LiPo batteries, a Victron DC to DC charger and a Victron smart shunt battery monitor, all configured by the same mobile rv guys.

 

That's how my system is supposed to be set up but my fridge will only run on propane (which of course requires a bit of electricity for the computer chip board or whatever, supplied by batteries) or shore power.

 

https://dcpoweronboard.com/battery-integrators/

Start with quality.

 

Basically yes, but the whole wiring from the trucks battery's to camper battery's must be made new and in heavy gauge, at least 2AWG. LiFePos can take an enormous amount of current in a short time so your wiring needs to be able to run up to 150A continously. This doesn't work with the telephone wiring that's in the truck now, with this only a small B2B is an option.
By default you can hardly overcharge the LiFePos with the Alternator as their charge end voltage is usually above what your Alternator puts out - except in dead winter.

 

But, if you have a Victron DC-DC charger this unit (which model/year??) should be able to know if the truck is running or not.
And this has to be the only way in for current to the Camper.
As you say your camper is from 2003 there might be wiring issues that take shortcuts around your B2B charger.

I've seen to many old campers with horrible hacked wiring in the last couple years on campgrounds with owners desperately looking for help to get it fixed.
Everything is just cheap cheap cheap, lousy assembled and then hacked by some shade tree DiY electricans.

 

I have a power manager in my slide in camper that will use the truck batteries to power the camper until the voltage goes down to 12.8 volts then it no longer draws power from the truck batteries. That way it charges when I'm driving or if I plug a solar panel into it. On a side note, when a fridge is running off 12 volts, they consume a lot of power. My fridge I can control whether it runs off DC 12 volts or propane so driving it's in 12 volt mode and once stop I switch it over to propane.

 

As far as I can tell, the fridge only runs on propane or shore power. It doesn't have a battery only mode. But it does require power when in propane mode for the circuit board.