12V DC power supply - 2 maximum cable meters?

[I Citro]

... Afterwards for HF or with strong harmonic currents it comes into play and there is still a whole calculation (which I do not know)
... the HF cable looks like for example a very thin metal pipe and sheathed, because anyway
the current does not use more than a few microns on the surface

This is why we use stranded cables to multiply the useful copper surface and thus reduce losses.

[Forhorse]

Also yes ... especially for the big sections.
Moreover, for very large sections, for this purpose we use so-called "sectoral" cable. The core of the cable is actually made up of several strands of triangular shape (themselves made up of many thinner strands) which are therefore assembled to form a round core but by inserting between each of them a sheet of semiconductor, thus accentuating the surface effect.
The strands of the cables of the airlines have a very particular form also for this reason.
For small sections the use of multiple strands is mostly a mechanical reason: flexibility

[Forhorse]

Well then, I took out the calculator and asked some equations.

It is long and tedious because it requires many postponement. So I took the time to calculate only the first branch (the longest) of the 1 9 lamps
I pass you all the intermediate calculations, it would be much too long.
In the end, I find that in this branch 2.021A 12A or 24.25V will be a power 27W (against XNUMXW theoretically)

I did not calculate all the branches either, it would be much too long, but simply the most distant
The 1 lamp should be powered under 11.8349V
The 2 lamp should be powered under 11.8308V
The 3 lamp should be powered under 11.8275V

In the last branch (lamps 1,2 & 3) we should measure 11.8375V
In the second branch (lamps 4,5 & 6) we should measure 11.8496V
In the first derivation (lamps 7,8 & 9) we should measure 11.8818V

I did not calculate exactly the dissipation in the cables (it would be necessary to do the intensity calculation for all the branches, something which I did not do) but it should not exceed the 3W if I am based on this that I calculated for the main line (2.39W in the line between the power supply and the first derivation)

These results are of course given for complete indication and this for several reasons:
- Precision calculations ... I did not report each time the decimal 15 behind the comma, so there is a rounding accumulation
- The LEDs are not purely resisitf receiver but semiconductors. Not to mention the fact that the lamps certainly incorporate a little control electronics, it is not possible for me to predict their behavior in case of power supply variation. So I did the math considering their equivalent impedance, which is probably totally wrong.
- The calculations do not integrate the resistance of the various connections (derivation, connections, sockets) which can go from very negligible to frankly important (socket of bad quality for example)

However, it appears that the sizing of the installation seems correct. The worst case being the 3 lamp, it is found that the voltage drop is less than 2% (1.4% exactly)

There's just

[Patatrace]

Waw what precision I tried to make the cleanest connections possible, we'll see the result when I'm done. I will measure the voltage 20cm before the bulb, at the level of the sugar which joins the cable 2,5mm² and the high temperature cable 1,5mm². The 2,5mm² cable is of rigid type.

[Patatrace]

Here is the result:

At worst we fall to -1,4%, which remains far from 3% admitted.



15 Elix 3W bulbs consume around 58W, which gives 3,87W individual consumption, which remains reasonable.

As you can see, I could not get the Elix 4led 1W bulbs to work (goodbye the 320lumens offered ...). Yet they work but not if we put them with the other 15. I measured a "cos phi" with this device of 0,55 with the 15 3W bulbs powered, which could explain that 3 bulbs from 4W did not start because this was a problem. (correct me if im wrong)

I did not know that we could not mix two different types of bulb ... I will have to put the same model, which bores me since I had the others with the nice reduction proposed I would have retested with the bulbs Velleman 5W sold on this site, but if it gives the same result I do not want to pay shipping costs.

Anyway hat in Forhorse