Roamer 230SB and seat base modifications

[EAN]

It’s something that I haven’t been able to get a definitive answer to, but I think you are right to question.
When you purchase power distribution blocks you see that the studs increase in size as the current goes up.
I found this article that gives some idea of the current carrying capacity.

Current carrying bolts

www.erichgeiss.de

The stud itself shouldn’t be taking the main current. It should be through the terminals and the surface contact area.
This depends upon how well it’s clamped, the size of the contact area and how conductive that whole contact area chain is.

 

[Skyliner33]

It’s something that I haven’t been able to get a definitive answer to, but I think you are right to question.
When you purchase power distribution blocks you see that the studs increase in size as the current goes up.
I found this article that gives some idea of the current carrying capacity.

Current carrying bolts

www.erichgeiss.de

The stud itself shouldn’t be taking the main current. It should be through the terminals and the surface contact area.
This depends upon how well it’s clamped, the size of the contact area and how conductive that whole contact area chain is.

Yes, I appreciate that its not the stud that carries all the current. Thinking about it, if the contact are between the lug and the 'ground' is large enough that is where the vast majority of the current will go, not through the stud at all. I will have a read of that article, but I dont see why the studs increase as current goes up as long as they can be torqued sufficiently. In fact I wonder if it matters much that the OEM seat bolts have the non conductive coating, as long as their is sufficient connection between the lug surface and the metal it is bolted to?

 

[EAN]

Yes, I appreciate that its not the stud that carries all the current. Thinking about it, if the contact are between the lug and the 'ground' is large enough that is where the vast majority of the current will go, not through the stud at all. I will have a read of that article, but I dont see why the studs increase as current goes up as long as they can be torqued sufficiently. In fact I wonder if it matters much that the OEM seat bolts have the non conductive coating, as long as their is sufficient connection between the lug surface and the metal it is bolted to?

The non conductive coating prevents / limits the electrical connection, so it does indeed matter.
There has to be a conductive path through the chassis and back to the battery negative.

 

[roadtripper]

The bulk of the current I think is carried through the non bolt surfaces - if you look at how the cube fuses work they have a totally insulated bolt and are rated at lithium like current levels.

If you are going to put high current connections on a chassis ground stud you want the high current ones on the bottom so they are in closer contact with the main body, and not trying to flow through many layers of ring connectors.

 

[EAN]

The conductive surface area of the connection through the whole assembly clamped together is key.
Ideally, the connection to the chassis should be a highly conductive surface of area of equal to the surface area to the terminal being clamped to it so as to minimise resistance.
Resistance is inversely proportional to the cross sectional area. Easy to understand with selecting appropriately sized cables but it applies equally to all the connections.
Power = current ^2 x resistance, so as currents increase it becomes more of an issue and problems occur such as local heating, wasted power, connection failures etc.. it applies to the whole current path of the circuit.

It’s one of the reasons Roamer state this in their battery installation instructions:

“Roamer do not allow the stacking of multiple high power connections on the battery terminals (maximum of two cable lugs per battery terminal). If you have multiple chargers and other components to connect, then you should use busbars or a distribution system. Too many cable connections on one bolt adds excessive resistance, which under high current flow can become extremely hot. Shifting any complex connection points away from the battery reduces the risk of fire arising from a failed, poor or loose connection.”

 

[Dellmassive]

i used the seat base to chassis bolt,

(and cut off the EOM stud and domed nut to allow the battery to sit flatter and not have the nut being a pressure point of the underside of the battery)

 

[roadtripper]

The conductive surface area of the connection through the whole assembly clamped together is key.

Yes it's the contact area between the chassis and the ring terminal that's important, along with the correct torque to make that so.

Correctly clamped all the current will be flowing through the bottom of the ring terminal that is in contact with the body. Current takes the shortest path, it's not going to significantly flow up the top surface, through the nut, through the bolt, through the weld and then into the same area of the body. The bolt can be insulated or not, often it can have anti shake washers to ensure the torque doesn't change.

This is a 200A cube fuse, that ring surface is carrying the entirety of that current as the bolt is insulated to provide the separation.





So long as you achieve the same on your ground point it will be fine. The only thing I'd really take extra precautions around is inverters due to the fact they have a huge current for a sustained periods of time, but then they are usually close to the battery so that's easier to achieve.

 

[EAN]

Taking using one of the seatbase mounting chassis studs as a GND point; there are a number of issues to overcome in order to achieve a decent connection (on a T6.1 anyway and I can’t see the T6 being any different).

The seatbase is painted so you have paint on the top and bottom surface being clamped.
The seatbase mounting studs are coated in an insulative protective coating.
The van is painted under the seat base mounting studs
So, if you don’t prepare the connection you are clamping your negative cable via 2 painted surfaces of the seat base via an insulative protective coating, which in turn is bolted down onto a painted surface.
So how good is your GND connection in that instance?
I would say it’s reliant on a bit of luck.

I used one on each seat and did the following to make sure I had as decent GNDing points as I could achieve, because my battery is under one seat and my inverter under the other. I also wanted to limit corrosion from exposing metal.

[Guide] Seatbase stud bolt Earth / GND connection

Thought I’d post how I did each of my GND connections through a seat base mounting stud bolt. I couldn’t use the factory GND studs under the seats because on the drivers side it had been removed to allow fitment of the diesel heater ductwork and on the passenger seat it was going to foul my...

www.t6forum.com

 

[Skyliner33]

i used the seat base to chassis bolt,

(and cut off the EOM stud and domed nut to allow the battery to sit flatter and not have the nut being a pressure point of the underside of the battery)

Did you do much preparation as in @EAN's thread?

 

[Dellmassive]

Did you do much preparation as in @EAN's thread?

i scratched the paint off, and used washers with the lug.



here you can see the stud, and both seat base bolts. - Fogstar Drift 12v 230Ah Seatbase battery -- "How I Done It" --





....


borrowing @sounds pic, i used this bolt and cleaned off the paint on the seat base.






been that way for years. . . the seat base showed next to zero ohms to chassis.

and i run the 1kw inverter and 50A charger over the link with no issues so far.

 

[Skyliner33]

i scratched the paint off, and used washers with the lug.



here you can see the stud, and both seat base bolts. - Fogstar Drift 12v 230Ah Seatbase battery -- "How I Done It" --


View attachment 261804View attachment 261805


....


borrowing @sounds pic, i used this bolt and cleaned off the paint on the seat base.



View attachment 261806


been that way for years. . . the seat base showed next to zero ohms to chassis.

and i run the 1kw inverter and 50A charger over the link with no issues so far.



View attachment 261808

View attachment 261807

Thanks. I'm guessing you must have relocated that thin brown wire that is on the stud circled in green.

 

[Dellmassive]

I never had that brown cable on my van.

Those pics are screen shots from deakys van I think.

 

[TJH1985]

Does the Roamer 230SB protrude above the seat base? For those that have non factory swivels that bolt flush with the top of the seat base.

Thanks