10m 2.5mm cable is 21 EUR in the local home improvement store
The problem I see is hours of sunlight. Assuming your charging source is PV then for example on a short winter day you will only be able to transfer 10AH to the battery.
Your 12v battery will not like being kept at 12v. It will need something like 14.4v absorbtion charge and then storage at a float voltage of something like 13.8v.
This seems like a very complicated and expensive solution to a problem that's not really much of a problem.
even 16sqmm wire is only £1.67/m and that will be good for <5% volt drop at 20A
How efficient is the type of converter you want to use? I much rather take the loss in the cable.
Does the solar panel have a built-in voltage regulator?
The last time I used a 12V solar panel, I found it had a much higher output voltage when open circuit, something like 18V. If you don't intend to use the full power output, you might find the voltage is high enough. Put the solar panel at one end of a thick cable and an efficient buck converter, with a low dropout voltage, near the load.
While 12V isn't optimal for transferring 120W, 10 meters is still just 10 meters! I bet just throwing more copper at the problem is the cheapest and most reliable solution.
To save myself hassle and making a mess of it. I phoned my rather casual spark to install 6mm2 and hopefully doesn't cost and arm and a leg. I don't think it will knowing him.
It will be twin and earth of course. I was thinking to parallel and get any advantage I would need 4 cores, but then I thought about it and adding the earth in parallel to the + might mean less voltage drops on the high side and overall circuit resistance will be lower.
To save myself hassle and making a mess of it. I phoned my rather casual spark to install 6mm2 and hopefully doesn't cost and arm and a leg. I don't think it will knowing him.
It will be twin and earth of course. I was thinking to parallel and get any advantage I would need 4 cores, but then I thought about it and adding the earth in parallel to the + might mean less voltage drops on the high side and overall circuit resistance will be lower.Why parallel with earth with the positive side? Is the negative side earthed? If so, parallel the negative with the earth. Otherwise, if it's not earthed, it doesn't matter whether you parallel the positive, or negative with the earth conductor.
To save myself hassle and making a mess of it. I phoned my rather casual spark to install 6mm2 and hopefully doesn't cost and arm and a leg. I don't think it will knowing him.
It will be twin and earth of course. I was thinking to parallel and get any advantage I would need 4 cores, but then I thought about it and adding the earth in parallel to the + might mean less voltage drops on the high side and overall circuit resistance will be lower.Why parallel with earth with the positive side? Is the negative side earthed? If so, parallel the negative with the earth. Otherwise, if it's not earthed, it doesn't matter whether you parallel the positive, or negative with the earth conductor.
No end is earthed. The earth conductor is redundant.
Although... is it?
What happens if it get's hit by lightening? Should I earth the cable itself?
Actually. I think earthing it would not matter. If it were to have the unlikely miss fortune of lightening strike, which is more likely if it IS earthed.... anything on either end of that cable or anything near it will be vaporised earth or no earth.
EDIT: The panel/battery system is 100% floating. Except whatever conductivity to ground the system has from any leakage via air or the bench it's sitting on.
I think I did measure it realitive to earth once and it was under a volt battery - to plug ring earth.
If it gets struck by lightning then you've got bigger problems to worry about and probably not much more likely if the cable is earthed, since the voltage is so high.
What happens if it get's hit by lightening? Should I earth the cable itself?
Actually. I think earthing it would not matter. If it were to have the unlikely miss fortune of lightening strike, which is more likely if it IS earthed.... anything on either end of that cable or anything near it will be vaporised earth or no earth.
What happens if it get's hit by lightening? Should I earth the cable itself?
Actually. I think earthing it would not matter. If it were to have the unlikely miss fortune of lightening strike, which is more likely if it IS earthed.... anything on either end of that cable or anything near it will be vaporised earth or no earth.
Ask yourself this: Would you rather have the majority of the energy from a lightning strike dissipated outside your office or inside?
If you earth the negative lead to a ground stake (earth) just outside the building and also connect the +12V line to the stake via a spark-gap it'll be a lot safer. It's up to you if you want to take the risk. Personally where I live I wouldn't worry about it since lightning is very rare here. But your location may be quite different.
So maybe, I should at least ground the solar panel system to a plug socket earth. Not to protect it from lightening, but to stop it floating to some silly ass voltage in electrical storms etc. I mean just because the once or twice I have measured it, it was within a volt of GND, doesn't mean it's always like that. It could get way off if there is electrical storm activity. No?