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Hello
Apart from the extra cost, can I use a larger section cable that is 4mm pass 10mm? Example use the surplus of the panel cable (10mm) to regulator to connect the regulator to the battery (4mm)? Is there an advantage to this or a risk?
Thank you in advance

Hello,
The section of an electric cable is expressed in mm² and depends on the current that flows through it and other parameters summarized here http://www.e-cours.com/2015/03/calcul-d ... es-en.html

Who can least the least. If the connections accept 10mm² you have no risk to put it in place of the 4mm²
On the other hand if you have to start tinkering because the 10mm² does not fit in the holes then there is more questionable.

But yes indeed, a larger section will only reduce losses by Joule effect.

I realize that I did not understand the question, but what holes are you talking about?

All this is related to a dimensioning.
- Between the panel and the regulator, the recommended cable cross section is 10mm2 for 10 meters.
- Between the regulator and the batteries (24v), the recommended cable section is 4mm2 for 2 meters.
I was planning to take 10 10mm2 cable meters knowing that this is an estimate. The question is If I will not use the 10 meters (example: 8m) can I use the remaining 2 meters to connect the regulator to the batteries in place is 4mm2 advised?

Forhorse wrote it well "who can do more can do less", but I too take a long time to relax.
If the wire is 10 mm², it will have 3.56 mm diameter and maybe will not fit into the regulator terminal, otherwise no worries and you have better to have the shortest possible links to minimize losses.

Thanks for your help. I am considering taking a 75 / 15 victron. For 8 meters distance, I am advised a section cable 6mm2. In conclusion, I will try to reduce the links.

it is necessary that the section is sufficient to pass the current without heating: it is indepandant of the length, if it holds on 1m it will hold on 100 m also

but the question is not that to support the current without heating, it is also necessary to see the voltage drop, the longer it is the more one has the risk that the minimum section makes too much voltage drop

so the longer it is, the more you have to increase the section

if we increase the section in the same proportion as the length the voltage drop is the same

if there is a certain voltage drop with 10m of 4mm2 there will be exactly the same voltage drop with 100m of 40mm2 ... we see that the increase in length is ruinous, both 10 times longer and 10 times bigger, so 100 times more expensive

in 220v we are less affected by the voltage drop and we can stay in minimum section until long distance ... but I still have an injector injector 2kw which fails over voltage because of a cable of 50m 2.5mm2 ... with 6mm there is no longer this problem

It does not matter if the increased section does not fit in the connectors .... it's the increase in section on the long length that makes the profit, there is no disadvantage to put a smaller length of section adapted lower to connections

Thank you for your answers.
Another question; How is the regulator's "load" output used to connect a 12v fridge and 1 or 2 bulbs? Otherwise if there is another method without using this output

The acceptable loss of voltage is indeed a function of the consumers and indeed, an inverter does not support a voltage drop upstream.
In the link given at the beginning, we count 2.5% (0.3 V in 12 V)

The regulator's "load" output is automatically cut off when the battery reaches a discharge threshold. The use must be connected to it.
It is a security to avoid deep discharge.

All of this should be normally noted on the record.