Solar cable size

[headlight]

I'm now getting 1.1amps more put in to the batteries than the panels are producing.
It must be magic

 

[Revolvor]

Sandancers
With an MPPT controller, Power in = Power out.

Power (watts) = Amps X Volts

If the panels are producing 400 watts @ 20 volts, then the input current is 400/20 = 20 amps.

However the output is still 400 watts (with very slight losses) so the output current at 14 volts is 400/14 = 28.6 amps

 

[Raul]

Sandancers
With an MPPT controller, Power in = Power out.

Power (watts) = Amps X Volts

If the panels are producing 400 watts @ 20 volts, then the input current is 400/20 = 20 amps.

However the output is still 400 watts (with very slight losses) so the output current at 14 volts is 400/14 = 28.6 amps

Agree, mppt= power in-power out. And i may add

Pwm=amps in- amps out @ battery voltage; significantly less watts, about 30% less.

 

[Raul]

I'm now getting 1.1amps more put in to the batteries than the panels are producing.
It must be magic
View attachment 748971

I know allot of ppl are hung up on amps. But, amps without volts are meaningless. Amps are only a indicative of current flow. Nothing else. You want to know the power, Watts.

 

[headlight]

I know allot of ppl are hung up on amps. But, amps without volts are meaningless. Amps are only a indicative of current flow. Nothing else. You want to know the power, Watts.

Yes, I was just pointing out to Sandacers that the MPPT will receive less amps at higher voltage from the panels then put more amps at lower voltage in to the batteries as he was saying that that was not possible.
Hence the screen shots.

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[Hoovie]

Output side to battery, 10mm2 will be okay, 16mm2 even better. This will be higher amps and lower voltage post MPPT magic.

20A solar controller and you would use 16mm2 cable? Wow!
Good luck fitting that cable into the terminal

 

[Raul]

20A solar controller and you would use 16mm2 cable? Wow!
Good luck fitting that cable into the terminal

If you crimp a ferrule you can fit a large cable, if you crimp a pin, you can fit a even larger cable. On the victron 6mm2 terminals, if you use crimped pins, you can fit 25mm2 cable. That, if distance calls for it. Design well and avoid it, of course.

 

[Hoovie]

If you crimp a ferrule you can fit a large cable, if you crimp a pin, you can fit a even larger cable. On the victron 6mm2 terminals, if you use crimped pins, you can fit 25mm2 cable. That, if distance calls for it. Design well and avoid it, of course.

you could fit 100mm2 cable if you REALLY wanted! But the simple answer is you DON'T NEED TO
You see it on lots of forums, but for some reason very frequently on this one, people quoting way over the top cable sizes, especially on solar cable.
I have a 300W 'external' array connected to my Motorhome via around 50 foot of extension cable with a gauge UNDER 1.5mm2. I measured with my DMM the voltage at the start of the cable and compared (live - so at the same time) the voltage the Victron controller reported. There was virtually no difference.

PS. the Victron 100/20 20A controller doesn't even take 6mm2 cable, the maximum is 4mm2.

 

[The Wino]

20A solar controller and you would use 16mm2 cable? Wow!
Good luck fitting that cable into the terminal

Given the wire length to the controller the cables from that the the battery are going to be pretty short too which makes it even more oversized to use 16mm2

 

[Hoovie]

If you crimp a ferrule you can fit a large cable, if you crimp a pin, you can fit a even larger cable. On the victron 6mm2 terminals, if you use crimped pins, you can fit 25mm2 cable. That, if distance calls for it. Design well and avoid it, of course.

Oh, just a little observation for fun ..... using a ferrule actually INCREASES the overall cable size. If you take the Victron Orion 30A DC-DC Converter/B2B Charger, the maximum cable size for that is 16mm2. If you put a ferrule on the cable, you cannot get it in the terminal connection any more! Useless! You can (and this is what I do) use a crimp pin instead as you say.

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