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Renewable energy: solar powerUse larger section cable?

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kau
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Use larger section cable?

Unread Messageby kau » 22/06/18, 20:20

Hello
Apart from the extra cost, can I use a larger section cable ie 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
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izentrop
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Re: Use larger section cable?

Unread Messageby izentrop » 22/06/18, 21:11

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
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Re: Use larger section cable?

Unread Messageby Forhorse » 22/06/18, 22:43

Who can do the 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.
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Re: Use larger section cable?

Unread Messageby izentrop » 22/06/18, 23:22

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?
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kau
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Re: Use larger section cable?

Unread Messageby kau » 23/06/18, 00:14

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 In case I will not use 10 meters (example: 8m) can I use the remaining 2 meters to connect the regulator to the batteries in place is 4mm2 advised?
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Re: Use larger section cable?

Unread Messageby izentrop » 23/06/18, 01:09

Forhorse wrote it "who can do it the least", but I too am slow to relax.
If the wire is 10 mm², it will have 3.56 mm diameter and maybe will not fit in the regulator terminal, otherwise no worries and you should have the shortest possible links to minimize losses.
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Re: Use larger section cable?

Unread Messageby kau » 23/06/18, 10:05

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. 8)
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Re: Use larger section cable?

Unread Messageby chatelot16 » 23/06/18, 10:38

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 takes, 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 2kw injector that fails over voltage due to a cable 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 of section on the long length that makes the profit, there is no disadvantage to put a small length of section lower adapted to the connections
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Re: Use larger section cable?

Unread Messageby kau » 23/06/18, 21:01

Thank you for your answers.
Another question; in what way used the output "load" of the regulator to make sure to connect a refrigerator 12v and 1 or 2 bulbs? Otherwise if there is another method without using this output
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Re: Use larger section cable?

Unread Messageby izentrop » 23/06/18, 22:13

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

All of this should normally be noted on the record. : Shock:
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