Ground questions for a 12v truck camper system

[Thergood]

Hey folks - Really appreciate the knowledge on this forum. I'm working a 12v system for my truck bed camper with some solar and DCDC charging. I feel pretty comfortable with everything except the ground situation. Forgive the poor diagram below. Also, please try not to focus on the numbers, I'm still working final calculations for a lot of this.

For some reason I cannot wrap my noggin around this. Is my negative design correct here? Do I need a separate negative cable going from the NEG bus bar to the start battery or common chassis ground at the front of the vehicle?

 

[justinm001]

Looks good to me. You want to add a chassis ground from the bus bar just incase.

The starter battery is a separate system so it's ground only needs to go to the mppt. You want a chassis ground on the house side just incase you have a wire that hits ground. This way it'll blow the breaker instead of shocking you

 

[Dave in AZ]

I disagree w justin on this, maybe. Depends what kind of "teuck camper" it is. If it is a slide in that may not be well grounded to the frame, and is separate from the truck with composites etc, then yeah-- make a single bond of the negative bus with chassis. AND your dcdc charger should be ISOLATED-- this is why victron has isolated and non-isolated chargers!

However, if your "truck camper is like mine, an aluminum popup bed topper, then it is NOT a separate system and it is all grounded. In this case, there should be only a single neutral to ground bond in system, at the atarter battery, and the dcdc charger should be non-isolated, which actually passes the bond thru from camper to start battery bond.

Here, read this, this forums basic mobile grounding primer from Beginner Resources:

Grounding Made simpler - Part 4: Mobile systems.

To get the paper, click on the orange button at the top of the screen. The subject of grounding is a complex, multifaceted subject, that is often treated as an after-thought but needs to be considered from the beginning of the design and build...

diysolarforum.com

 

[RV8R]

Hey folks - Really appreciate the knowledge on this forum. I'm working a 12v system for my truck bed camper with some solar and DCDC charging. I feel pretty comfortable with everything except the ground situation. Forgive the poor diagram below. Also, please try not to focus on the numbers, I'm still working final calculations for a lot of this.

For some reason I cannot wrap my noggin around this. Is my negative design correct here? Do I need a separate negative cable going from the NEG bus bar to the start battery or common chassis ground at the front of the vehicle?

View attachment 205415

@Dave in AZ makes a good point regarding “grounding”, but details matter & I do not believe you listed the DC2DC.

You main battery fuse is 200 A but your total on the load side is 300 A .

2000W inverter @ peak will draw how many amps ?

A 4 way switch ( Blue Sea 9001e ) might be configured to be a switch & positive bus;

e-Series Selector Battery Switch - Blue Sea Systems

350 Amps continuous rating for inboard gasoline or diesel engines.

www.bluesea.com

No need for wire between shunt & neg bus ,,, just bolt on a copper bar as neg bus.


Other electrical items that might work well for you;








I really like my Kisae 1250 ( Alternator & Solar Charger ). Adjustable from 5A to 50A ( in 5 A increments ), plus other user programable settings.

DMT1250 – Kisae Technology Inc

Kisae now makes a 12100 ( 100 Amps max ).


Not sure about your needs, but the “Safety Hub 150” from Blue Sea might “fit your design” for a central fuse block ,,, especially if your inverter would not stress it out;

SafetyHub 150 Fuse Block - Blue Sea Systems

Ignition-protected fuse blocks capable of consolidating and protecting multiple 1A to 200A circuits.

www.bluesea.com

If you list your choice of equipment & why you picked it out, I might be of more assistance to ya.

 

[justinm001]

I disagree w justin on this, maybe. Depends what kind of "teuck camper" it is. If it is a slide in that may not be well grounded to the frame, and is separate from the truck with composites etc, then yeah-- make a single bond of the negative bus with chassis. AND your dcdc charger should be ISOLATED-- this is why victron has isolated and non-isolated chargers!

However, if your "truck camper is like mine, an aluminum popup bed topper, then it is NOT a separate system and it is all grounded. In this case, there should be only a single neutral to ground bond in system, at the atarter battery, and the dcdc charger should be non-isolated, which actually passes the bond thru from camper to start battery bond.

Here, read this, this forums basic mobile grounding primer from Beginner Resources:

Grounding Made simpler - Part 4: Mobile systems.

To get the paper, click on the orange button at the top of the screen. The subject of grounding is a complex, multifaceted subject, that is often treated as an after-thought but needs to be considered from the beginning of the design and build...

diysolarforum.com

I totally agree with you and in theory this is the best option to eliminate ground loops. But the point of adding an additional ground at the house bus bar is an additional safety measure. Because OPs house system is completely home run there shouldn't be anything going to frame ground, unless there's an issue.

If a large system like mine in a large RV with a Ton of power and multiple systems, having a chassis ground for each system is the safest play. Otherwise if there's an issue and say a large battery bank 48v 4/0 cable hits the ground, it'll have to travel through the entire chassis to the starter lug, through the equipment until it got to the 48v battery ground. Potentially pumping like a thousand amps. On top of this it's normal for trucks to frame ground a lot of their devices so everything's travelling all through everything.

Running a chassis ground from each buss bar and from each major piece of equipment is a safety measure so any issues can find the path of least resistance, trip the breaker and not risk blowing devices. Worst case you get a ground loop which just causes a bit of RF radio interference.

Very similar feature house 120v electrical systems use with their grounding system

 

[S Davis]

Which dc/dc charger do you have. I use a non isolated 50amp Redarc, with a dedicated positive and negative. My inverter is a victron that automatically switches the neutral ground connection. Inverters ground goes to negative buss bar which is bonded to the frame in the engine bay. If your using a isolated, and that is what your diagram looks like you will need to make a bond to the frame.

 

[0truck0]

I had a fiberglass truck camper (slide in camper, not a lid topper cover). There was literally no metal in the camper to ground to. The only ground was the neg cable going to the truck. I had solar, one battery on the camper, and two big ones in the truck bed that were grounded directly to the frame close. That was the ground. These were all LA batteries, not lithium so I didnt care about running a neg cable back to the starter battery.
Other than the extra batteries in the truck, this is how the manufacturer intended it, thats not saying much as RV manufacturers are notorious for being among the dumbest, but it did work.
The manufacturer's ground was just the 7-pin wire from the trailer plug, which came off the rear bumper, then up to the front of the camper, long run and again stupid. I changed it so i had power to run through the side of camper directly to the batteries to the frame, so 3 feet max from camper to the frame, and bigger cables of course.

Normally truck campers would also have ground through the chains and turnbuckles that attach the camper to the truck outriggers, all metal, and the inside of the camper has metal brackets that touch more metal and act as a ground for the camper to truck. If it is fiberglass then no such ground exist.. Not all truck campers are the same, only yours matters to you.