Wiring a SmartShunt When Trailer has 3 Chassis Grounds

[RV Steve]

I'm trying to figure out how to route all loads through the "Load Minus" terminal on my IP65 SmartShunt when my 2021 Outdoors RV Blackstone 280 RKS trailer has 3 chassis ground connections for the 12 volt system and one chassis ground for the 120 volt. I currently have 2 x 6 volt lead acid batteries in series located on the front triangle as is normal on many travel trailers. The negative terminal of my battery bank is grounded to the frame. Under my pass through storage there's a 12 volt breaker compartment with a negative busbar that also has a chassis ground. Then in the middle of the trailer at the Progressive Dynamics 4060K power converter/load center there's a third 12 volt chassis ground; a 120 volt system chassis ground is also present at this location. I understand that all loads need to be connected to the "Load Minus" terminal of the SmartShunt so it appears this would require re-routing two of the existing chassis grounds. Disconnecting the battery bank chassis ground and running a negative connection to the negative busbar under my pass through storage is easy. I'm not certain how many amps that negative busbar is rated for or what wire gauge it will accept; there's a 6 AWG insulated chassis ground wire hooked up now. I'll need at least a 1/0 ground wire once my system is built out with LiFePO4 batteries and an inverter. Disconnecting the power converter/load center chassis ground is more involved. I called Outdoors RV today and they couldn't confirm whether all of my 12 volt circuits are connected to the negative busbar under my pass through storage. So just unhooking the power converter/load center chassis ground could leave some of my 12 volt circuits ungrounded. My best idea to deal with that is to extend the power converter/load center insulated 6 AWG chassis ground wire 12 to 15 feet up to the negative bus bar under my pass through storage. Then use one chassis ground for the entire 12 volt system from the negative busbar under my pass through storage using the existing 6 AWG chassis ground wire at that location. Suggestions to simplify this are welcomed!

Question: Would the SmartShunt work correctly if I skipped disconnecting the power converter/load center 12 volt chassis ground? I'm thinking any 12 volt circuits grounded at the power converter/load center location that aren't grounded at the under the pass through storage negative bus bar would run through the chassis to the pass through storage chassis ground, pass through the shunt, and on to the negative terminal of my battery bank. Is that correct?

I would also like to hook up a temperature sensor to my IP65 SmartShunt but it doesn't have the ferrule pin connections that are on the IP21 SmartShunt. The diagram in the manual appears to be suggesting splicing into the auxiliary input wires hardwired onto the IP65 SmartShunt. Any firsthand experiences and tips on that subject would be appreciated too.

I will be moving my battery bank to my under bed storage when I upgrade to LiFePO4 batteries and add a MultiPlus at that time. I will have the money to do that in 2-3 months. Then I'll have 600 amp busbars with 3/8" terminals and could run a larger chassis ground wire.

Here's a picture of recommended shunt wiring found in another thread. Sorry I don't have the ability to put together a schematic of my system on my computer.

 

[HarryN]

See if this diagram helps or not.

Safety grounds ( metal cases to van frame ) are not usually tied through the shunt. There isn't supposed to normally be current in those wires.

 

[RV Steve]

See if this diagram helps or not.

Safety grounds ( metal cases to van frame ) are not usually tied through the shunt. There isn't supposed to normally be current in those wires.

I'm not sure if I understand. Are you saying that there's little or no current running through the grounds at my power converter/load center and under pass through storage negative busbars? If that's correct then I would only need to put the shunt between the grounded negative busbar and the battery bank negative and disconnect the battery bank negative ground.

 

[Rocketman]

RV Steve - Your picture is correct - put the Smartshunt connected to the battery’s negative post - and no other items on the negative post, then comes the Smartshunt- then on the Charger/Load side of the shut is all the connections- including the ground to the frame, the negative to the inverter, the negative to the bus bar area- everything!!!

Did that clear up your question?

 

[Q-Dog]

I think you may be confusing grounds with negative on the DC system. On the DC system, power has to flow back to the battery to complete a circuit, and the frame of your trailer is likely used to complete the negative circuit back to the battery. Think of the frame as a huge bus bar.

 

[HarryN]

I'm not sure if I understand. Are you saying that there's little or no current running through the grounds at my power converter/load center and under pass through storage negative busbars? If that's correct then I would only need to put the shunt between the grounded negative busbar and the battery bank negative and disconnect the battery bank negative ground.

Connect the (-) side of all of the chargers and loads into the fuse block or load ( -) bus bar, depending on the amount of current involved.