Is this good enough ground

[u/Miisu123]

Can I use seatbelts bolt to ground my bus bar to ground and then install both negatives to the bus bar of my isolated dcdc charger to use it as non-isolated? Or should I carve the wood from under and install the ground directly to the bar under the plywood. Or is it best to just install both negative and positive to starter battery?

[u/Enginerdiest]

I wouldn’t use the seatbelt post. It may work for a while, but grounding issues are a royal PITA to troubleshoot, and I don’t think the post is reliable. 

Is your house system grounded to the chassis as well?

What van?

Without knowing more, I would probably attach to starter negative rather than chassis ground on one side, and your negative bus bar on house side. 

[u/Miisu123 → u/Enginerdiest]

Haven't installed house system yet. Starting from the ground so I can start installing the charger and lifepo4 battery. I was first planning to install both wires from the dcdc charger to the second closer starter battery. But It would require making 2 holes to the floor the get the wires from under the car(where battery is) to inside. But I was thinking if I used my orion tr smart isolated dcdc charger as non isolated and installed the negatives inside the van to chassis. Never done chassis ground so I'm a bit unsure what is the best choice to make. The van is g20 Chevy van

[u/DavidDaveDavo]

From an electrical standpoint it's not good practice to use a structural fastener as an earth connection. An earth connection should have it's own attachment specifically for the purpose of earthing.

That bolt and its thread would need cleaning. The paint needs to be removed on the seatbelt anchor and the metal of the chassis.

The reality is that it'll probably be fine, but it's not good practice at all.

[u/CasualEveryday]

No single ground is good enough... You always want at least 2 if you can. With a single ground, the actual grounding point electrically (place where voltage is exactly 0) is probably within a cable or the chassis itself. That means it's different for different circuits based on their individual resistance and consumers. Having multiple grounds evens the potential out and helps prevent poor grounds damaging your electronics.

[u/Bittenfleax]

I'm assuming you have a non isolated model of the charger.

It can work but personally I see two risks:

• Only the bolt threads are conducting. You're asking the current to pass through the seat belt anchor which may have coatings or be less conductive. Even if you remove the paint underneath and grease it with Unial Electric Grease Paste

• Seat belts are the one thing in a vehicle I don't fuck with. Even if you torque the bolt back down to original spec, you've just added a failure point to a safety device.

[u/xgwrvewswe]

No. The cable lug must be against clean metal, not the threaded bolt and defiantly not wood.

It is always better to have a negative cable to the source. (battery or to the engine block).

[u/Rubik842]

No. definitely not, you also don't want wood sandwiched in your seatbelt attachment.

[u/Miisu123 → u/Rubik842]

Is wood between seatbelt and nut that is welded to frame that bad? Rear seat is also an "hard bench" so it doesn't require seatbelts :D

[u/Few_Cup977]

Clean the paint of the vehicle side so it's bare metal. Use some dielectric grease to protect it. Otherwise, yes that should work as a sufficient ground.