Regarding the grounding of the battery in an off-grid system (either the negative or the positive pole), I seem to find contradicting information on Victron’s website.
The difference is the first diagram you have shown is a mobile installation like a boat where the hull is connected to system ground such that a live connection to the hull can not make the hull live and creates a path for current to flow allowing fuses or breakers to trip. A live hull can give shocks to people boarding the boat or swimming next to it.
A domestic system does not have the same issues. The local electrical codes may stipulate what is required rather than info on an international forum.
In a residential off grid system the battery DC negative should NOT be connected to any ground.
If there is a SEPARATE groundscrew on the case of the battery that should go to ground but NOT the poles themselves, either neg or pos.
Think grounding negative can be dangerous.
In case of a isolation failure of one battery, and if battery casing is grounded there can flow huge current.
And if negative isn’t fused you can’t stop it.
Maybe found a way to measure isolation current and generate an warning.
Have still to play with resistor values, but basic this works and keeps the negative near ground potential.
Why not implement an isolation check if grounding of battery negative is not needed?
Or what are the rules in the Netherlands, do I need ground negative or not?
In mine opinion grounding case and battery negative is dangerous in case of a cell isolation failure.
Or the battery must have an internal fuse in negative path.
99% of the topics I read about grounding is like a bloody tragicomedy. I’m laughing and terrified at the same time. Stop dishing out daft & downright dangerous advice on this!
Anything to do with designing electrical installations should only be handled by a proper electrical engineer. Note, not an electrician fitter, but specifically an electrical engineer.
They’re the only ones qualified to make decisions based on technical conditions, the specifications of the equipment in the setup, and all the safety rules and local laws.
Why wouldn’t an internal fuse on the positive side work just as well? Why are the batteries in all cars grounded to negative if it is supposedly so dangerous?
Because it’s an isolated chain & it’s similar to the TT system.
UPD: It’s the same as asking whether you can combine two grounding chains for AC and DC.
The simple answer is No, but there are cases where you could say Yes.
I’m not an electrical engineer, but a physicist. I know the theory, but I don’t know the practice or the regulations. But if someone accuses Victron of electrical engineering heresy, then I know who to trust. By the way, my first objection was about Ron’s statements, which I believe are false. But perhaps it’s more important to you to pursue alleged heresy than to have a factual discussion.
Victron makes recommendations that I fully agree with it.
I even agree with grounding the pan on an induction cooktop!
But Victron, like me, says the same thing - follow local norms and regulations and consult engineers for design.
Do you understand the difference between general guidelines, actual conditions, equipment schematics, safety rules, and regulatory grid standards?
To make the right decision, all aspects must be considered in each specific case. Not template solutions & recipe here.
And one of the most important aspects is not to insult others when discussing technology. Maybe you are actually a competent expert, maybe not. But in any case, you are someone who is incapable of discussing technical issues publicly.
Victron has published guidelines for grounding Victron systems, and these are by no means heretical or incompetent as you claim.
You are too sensitive, I don’t see any insults. I just can’t stand stupidity, heresy and advice that endangers other people!
The Victron company completely agrees with me on this!
If battery casing and battery negative is grounded and one of the cells has an isolation defect (connection to casing) you will have a full short.
Current flows through casing to casing ground cable from ground cable back to battery negative, and if there is none internal negative fuse in the battery bad thing can happen.
99% of the topics I read about grounding is like a bloody tragicomedy. I’m laughing and terrified at the same time. Stop dishing out daft & downright dangerous advice on this!