Grounding to chasis questions for 12v (only) van electronics

[electroniclearner820327]

Grounding has been a source of much confusion for me lately.

When I initially installed my basic 12v system in my van, with only a single 100ah battery, from what I read online grounding to chasis was not essential due to the small loads.

I am speaking here only about for safety in malfunction cases, not the other idea of using chasis ground as the 'return' route of the negative for purposes of saving on wire to eschew using a negative wire at all. Although the former may also necessarily imply the latter that is not what I want to do it for but due to 'best practices' that people keep telling me of online.

Now up until now my leisure battery wasn't linked to the chasis at all and rather 'free floating' as I have seen it termed. No issues but would often get the comments of 'you should really ground to chasis' if it came up.

I have recently bought a dc-dc charger, sterling power's bb1260. I was again told I really want to ground to chasis now more than ever due to the rather large amps that will be flowing through the wires.

Apart from a brief test, I have not connected it up properly yet.

Having read much more on the subject and received advice both on and offline I am wondering, if the starter battery will be linked to a negative busbar and all other leisure negatives are linked to that busbar, including the leisure battery, and given that the starter battery is ground to the chasis under the van hood, is there any point in making yet another chasis ground in the habitation space?

The only issue I can think of might be the wire sizing but the size I have currently from starter to leisure is 110a rating and the leisure battery is only 105ah. The only questionable bit of wire will be from the starter battery to the chasis ground which looks maybe 16mm2 but might be thinner. The question is whether just using that as ground alone for everything, including habitation electronics, is fine from a theory (and practice) perspective.

I have had comment that it should not be done due to some kind of shunt that ford vans have, which would be bypassed by doing. This seems to only be relevant to later models though and I don't think mine has it being 2007.

The dc-dc connection, as per the sterling instructions which expressly state to make a full wiring connection, and not use ground as negative, will be: starter positive to dc-dc charger input positive, starter negative to negative busbar. Charger negative to negative busbar and charger positive output to leisure battery positive. Also, as stated, all other habitation negatives to negative busbar.

So, as such, can I just forget about any more grounding to chasis since everything should be grounded to chasis via the starter battery's existing chasis ground right? No point making things more complicated than they are already right and the ford's own ground is going to be the best isn't it? Ok it isn't that clean which may be something to think about but still better to work with what I have already eh rather than reinvent the wheel?

So is there any advantage or point in making yet another ground to chasis point in the habitation space or will all the malfunction ground to chasis concerns be automatically taken care of with that link to the negative of the starter battery which is grounded to chasis already?

Also another side question. When people discuss using the chasis as a negative return instead of a dedicated negative wire to complete the circuit how is than not a shock risk if current is flowing all through naked metal rather than insulated wire?

[Whales]

Electrical safety is a complex topic, to give anything resembling advice we need a full picture. 

 - Can you provide a full list of all appliances, modifications and voltages that you have added to your vehicle? 
 - Do you have any 110V/230V wiring, appliances and/or inverters?
 - Can you provide some photos of your system, in particular of all batteries and connectors to the outside world?


> I am speaking here only about for safety in malfunction cases
> When people discuss using the chasis as a negative return instead of a dedicated negative wire to complete the circuit how is than not a shock risk if current is flowing all through naked metal rather than insulated wire?

Cannot comment on safety & malfunctions without knowing full detail of what appliances & voltages you are running.  12V alone is not a shock hazard unless you are doing subdermal things (tattoo studio in the van?), it's considered ELV (extremely low voltage), it only causes other types of hazards like burns and fire.  But you might have more than 12V by the sounds of it?