checking earthing point quality

[Leadfold]

I am installing a simple 12v system, key components being:

• Victron Orion-Tr Smart isolated DC-DC charger 12/12 - 30,
• Victron blue smart IP22 mains charger 12/30
• 230ah 12V LiFePO4 Roamer Lithium battery

I will be grounding the negative terminals to the van body, with 16mm² cable. I plan to test the resistance between components with a multimeter (for example stick a probe on the vehicle battery neg terminal and the other on the DC-DC charger input neg terminal). So my questions are:

• What reading should I be looking for on the multimeter to show a good connection?
• Is grounding to the vehicle body the right way to go, or am I better off running a negative cable between them?
• Is this cable chunky enough?

Thanks for any help

 

[Dellmassive]

0.0 ohm off load

yes - always best to use the chassis ground. ( or busbar thats connected to chassis ground )

16mm2 cable is mentioned in the install guide for the 12/12/30 Orion. due to the terminal input size.



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but it depends on the length of the cable run, fatter cable is always better.

https://www.victronenergy.com/upload/documents/Datasheet-Orion-Tr-Smart-DC-DC-chargers-isolated-250-400W-EN.pdf

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more info :

Dellmassive’s "How I Done It" blogs.

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[Leadfold]

Thanks for the reply. At a novice always good to have a plan confirmed by someone who knows what they are doing. Cable runs are less than 2m. So I thought I was good to go with 16mm.

 

[Leadfold]

Just put a multimeter on my my chosen earth point for my DC to DC charger. With the Ohms scale set to 200 I get a reading of 00.6. as a reference, probe to probe is 00.2 and the resistance along a 5 m length of 16 mm2 copper cable is also 00.2.

I'm not sure how to translate what I'm reading here. Does this suggest this earth point is going to function as I require it to? That is to run the DC to DC charger without issue?

 

[Dellmassive]

Got a pic of the location and setup?.

Sounds good though

 

[Leadfold]

Nothing is set up as yet, as was checking I have good earth before locating the charger. The earth is under the front passenger seat. The charger will be fitted to the lefthand outside of the seat base. It will be above the doorstep, so plenty of airflow. I'll send a picture once it is installed.

Thanks as always for the help.

 

[Dellmassive]

There is a chassis ground stud bellow both seats... And a seat base bolt.

 

[Leadfold]

Is it acceptable to have connect three ground cables to the same earth bolt? (In this case it is the input and output ground for the 30amp DC to DC charger and the the earth lead for the 30 ampmains charger. Obviously the two chargers won't be used at the same time. See photo

 

[Pauly]

Yes its fine, as long as theres still enough threads showing on the stud to get a decent purchase on the domed nut then you are fine

 

[Dellmassive]

As above, that's fine.

Fyi you can run multiple chargers at the same time, they work independently of each other.

 

[Leadfold]

Thanks folks