Electrical earthing on camper

G'day, I have just built up a trailer and used 2 x 105amp/hr LiFePo batteries and earthed everything back to the batteries. Much easier that way, no earth issues with trailer plugs etc. Just my two cents worth. John

I agree....steer clear of earthing via the chassis.

Why not run twin core wiring to your various appliances. They don't all need to terminate at the battery, creating a jumble of wires. You could run a heavy +'ve to a suitable fuse block and a similar -'ve to a suitable common earthing point that will accommodate all your various earths. This could be an 8mm bolt or two or three, fixed to a suitably robust mounting. That way accessing/changing your battery will be must simpler and also neater.

Hi Keith,

In general, electrical corrosion occurs when there is some difference in potential (voltage) between two electrically conducting components. Therefore it is reduced if all such components are well bonded to each other, and potentials produced by volt-drop of currents flowing in components such as the metal body or chassis are eliminated.

This is best achieved if the return current paths from the various loads in the camper are not returned to the battery via the body or chassis but by a dedicated negative return wire to a negative link bar connected directly to the battery. This requires a two-core (+ & -) cable to each consumer with no connection to the chassis. It also reduces losses due to volt-drop and is much easier to wire and troubleshoot with this arrangement.

In the case of vehicles, single wire with body/chassis return to battery negative is used because it is cheaper and the low current flows in most cables makes volt-drop and corrosion less significant.

Sometimes the camper battery has the negative side bonded to the chassis but it makes little or no difference.

Yes run the earth/gnd/neg to each "appliance", nothing but trouble with using chassis as the neg return.
The best and tidiest way is to use the typical twin (red/black) in a black sheath available from places like Caravan Plus in an appropriate size for each appliance and use a quality fusebox like the Baintech ones with inbuilt negative connections here

Thanks heaps. Looks like a unanimous vote to wire it like a boat, with a common earth bus.
Keith

Further in support of wiring everything in two wire cable and perhaps not connecting negative to the chassis at all.

The notion of earthing is completely foreign to DC 12 volt electrics.

The only reason you would connect the electrical system to the chassis at all is to save on running a return wire to negative battery.

I know some may argue the point, But I do not believe there is any good reason to bond negative battery to the chassis at all.

Always best to have a full circuit of positive supply and negative return wires.

cheers

Keith,

Are you going to use a battery monitor? With LiFePO4 batteries, I think you should because you MUST guard against over-discharge. Because they have such a flat discharge curve you should count amp-hours in (from your charging sources) and out (from your loads) to help determine the SOC. Monitoring voltage helps, but with that technique it's a fine line between being on the minimum and disaster. Monitoring amp-hours helps considerably as long as you have a reputable battery monitor (Victron, Synergex, BEP are suggestions).

Therefore, follow the advice in the above replies, but put the shunt for your monitor between the common negative and the battery negative.

Cheers

Thanks for all the help.
Yes there will be a full battery monitoring and management system. These batteries are too expensive to risk damaging them.
Keith