Non-Isolated DC/DC Charger in Truck Camper

[jhickok]

Hi folks,

I ended up with the Non-Isolated version of the Victron Orion-Tr Smart 12/12-30A DC-DC Charger because I rushed in ordering, and I thought "no problem," this one is okay (based on what I had read).

Now I am wondering, is it okay for a truck/camper setup? Or do I need the isolated version? I did email Victron, but wanted to set this up today and might not hear from them for a few days until the work week starts. Is this non-isolated version strictly for things like vans, RVs, and boats, that clearly share the same chassis... while a cabover camper actually sits on top of the truck?

I have a hard-side camper sitting on the bed of a Ram 2500 4x4 Diesel. Do they share the same negative return? Ground? Since they are sitting together... or are the negatives separate systems?

Can I still use this non-isolated version of the DC/DC charger, which has a positive input and a positive output, but ONLY ONE negative port (see photo attached)? Would the charger just connect to the ground negative for the camper? Do I have to run a negative from the truck's starter battery and connect it to the camper's negative system somehow?

Here is the diagram straight from Victron for this non-isolated model (attached). Also linking to the manual here.

 

[lmwilco1]

Your camper ground would need to run to the truck battery ground, most likely it already is if you have any running lights on the camper. Make sure to put the recommended size fuse for the wire that you are running as close to the battery as possible to protect the circuit. Make sure to run a large enough wire so the voltage drop is not too high and you will be good to go. Many people use Anderson Power Pole connectors as a disconnect int he bed for this type of installation.

 

[jhickok]

Thanks lmwilco1 - The camper is connected via the trailer hitch for lighting. Fuse will be in place directly at starter battery, and Victron also recommends one between the charger and the service battery (close to the service battery). I guess I would be good then with the non-isolated charger, as long as the trailer harness is connected.

So based on that chart I posted, should the DC-DC charger negative connect directly to the service (camper) battery? It seems like I could also connect to the nearby negative bus right off the battery too, right?

Your camper ground would need to run to the truck battery ground, most likely it already is if you have any running lights on the camper. Make sure to put the recommended size fuse for the wire that you are running as close to the battery as possible to protect the circuit. Make sure to run a large enough wire so the voltage drop is not too high and you will be good to go. Many people use Anderson Power Pole connectors as a disconnect int he bed for this type of installation.

 

[Vic Harder]

The non-isolated version is fine.
The whole point of a buss bar is to keep the connections on the battery posts themselves to a minimum.
If you have a Battery monitor with a shunt, you connect the ground to the shunt, not the battery
Running long wires carrying power coming from both ends... there should always be fuses/breakers at both ends.
I would not rely on the trailer plug for power. Those are usually 14g at best.
Run dedicated positive and negative wires (6g would be fine) all the way from the truck battery to the camper.
Mount the DC-DC where it has some cooling. They can run very hot.

 

[jhickok]

Thanks all! I did the install. 60a breaker on one side and 60a fuse on the other. May end up setting up a some kind of larger plug at the back of the truck to facilitate the disconnect. Negative from DC/DC charger and negative from starter battery meet at the camper battery.

I only have a monitor on the load, but will install one on the charging side later. I did install my shunt on the charge temporarily just so I could see the charging amps coming through. It was charging at about 5 amps which seems kind of low given that the DC/DC charger is 30a. I must be losing a lot in the wire runs, which are about 25 feet from the starter battery to charger. Used 4 gauge the whole way to the service battery, and the manual recommended minimum 6 (or really 16mm). Or maybe my alternator needs to get tested, but I think it's good. Or maybe while actually driving highway speeds, the charging amps will be higher because I was observing during idle.

 

[lmwilco1]

5A of charge current seems very low unless your camper battery already fully charged. If it is then you won't see much current flow. If it is not fully charged then you have some issue, maybe connect via bluetooth and see what it is doing.

 

[Vic Harder]

The orion has bluetooth, so use that to check the charge current. I get 33A out of mine.

 

[jhickok]

My model does not provide amps. The app/Bluetooth just shows input and output voltage (14.5 and 14.4). I think I saw somewhere that was "coming later" to monitor current.

Since I have no monitor hooked up, I won't know the charging amps for now - just voltage. Would install a monitor for charging if I had time, but leaving on a trip now. Just going off what I thought I saw initially for amps, which was very low.

The negative is not connected directly to the starter battery, but instead is connected to a common bolt with another negative ground on the frame 10 inches from the starter battery. That terminal runs to the starter battery via a smaller gauge wire, like 12 --- is that a problem? Does the 4g fatter wire need to connect directly to the starter battery before running back to the camper battery, rather than the last 9-10 inches through a smaller gauge wire?

Or would it be more likely to be a connection? Although there aren't many and I think I made them good connections.

Or did I make a bad decision to connect the negative from the starter battery AND the negative to the charger both connected to the negative terminal on the camper battery?

 

[jhickok]

Quick sketch of what I did... not expecting anything, but hoping someone will say, "ooohh," that's what you did wrong. I want to make sure I get closer to 20a+!!

When I saw the low amp charging current, when I did have my shunt temporarily connected, would the low charging amps be a result of mistakenly having two washers between the battery terminals and the lug?

And also, does it make sense that my monitor on the battery load shows my amps going up from about 0.15a to closer to 2a after starting the truck? If so, why would they go up... what extra load is on the camper battery DC when the truck is running? Is it the Orion device itself using those amps, but that should all be coming from the alternator/source?

 

[lmwilco1]

I would connect the 4G wire to something better than the 12g wire, it is probably not limiting your current but in the event of a short circuit somewhere that 12g wire could become your fuse. Either connect it to the battery or follow the neg battery terminal fat wire to where it goes and connect your 4g wire there.

 

[jhickok]

Vic Harder - You say the Orion has Bluetooth that measures amps... which model are you using? With the Orion-Tr Smart, the app does not report amps/current through the app. Just voltage. Just wondering how you are seeing current via Bluetooth and if you are using the non-smart version of the Orion or something that is different?



The orion has bluetooth, so use that to check the charge current. I get 33A out of mine.

 

[Vic Harder]

I’m looking at my BMV to get the amps. Sorry if I caused confusion!

 

[Jack]

In Power Supply Mode, the Orion DC-DC screen displays "Output voltage is kept constant and current limited to the configured values on the settings page". So maybe Victron will someday get "current" and display it.