Leccy a simple man's way of looking at it. Think of the flow of electrons like water flowing down a pipe. We can visualize water, but we can't see said electron flow. On my particular build I have solar which charges the battery......a gizmo called an orion TR smart........a B2B a battery to battery charger and also a battery charger that runs off mains.....off the EHU electric hook up . So potentially 2 of those 3 could be charging the battery at the same time. Put that another way actually all 3 could be in use,but it's unlikely.
So then folks wonder if those 3 different gizmos will interfere with each other.well basically no.
Lets go back to my simple water 'n' pipes analogy.lets think of our battery as a bucket, which we are filling/charging with 2 or 3 sources.pipes. We stick 3 pipes in a bucket the bucket fills faster same with our battery being charged with differing sources...solar B2B (runs off van alternator) and mains . The pipes don't mess with each other ,just the bucket fills faster.same with leccy/battery.
With 12 volt circuits our cables are much thicker than with 230V. to carry the same wattage. This is because the cable has to carry many more amps W= VXA watts equals volts multiplied by amps......................
so because the voltage is so so much lower are amps get ramped up.
Going back to water and pipes......if we have a tiny pipe and try to bang alot of water through it the water get pressurized pipe is put under duress it might burst.
Similar with 12 volt cable runs.....only the pipe/cable doesn't burst it's liable to over heat.
So we use a voltage drop calculator like this
Use our Voltage Drop Calculator to select the correct Cable for your campervan, motorhome or boat wiring application. Auto and Marine Electrical Components from 12 Volt Planet - Cable Size Calculator
www.12voltplanet.co.uk
to make sure we are using cables suitable for purpose over the length of cable run we need.
guys as above not a sparky, what I'm trying to do is give a base mindset and linkies to reading that will give the next guy a hand with his or her endevors.
See cable is expensive so converters try to skimp fire is the worst case senario, but just voltage drop alone can be enough to stop things like fridges from working.
It's worth while me running through this stuff on a very basic level.
With a van leccy system we are dealing with a moving senario, so we have to use fine stranded copper cores in our cables,not single strands like in a house.this is because copper can "work harden" in other word become brittle with vibration.multistrand cables cope better with the vibration caused when driving.
All our connection points are a weakness......so we tend to crimp with large forces ( a cold weld) and then add a layer of heatshrink to strengthem the join. We can also bind looms in fire resistant cloth tape, which also damps noise. Supporting joints with cable glands, say in a consumer unit is also really important.
I guess what I'm trying to get out is it's just worth going the extra mile with camper leccy and after a couple or 3 years of reading I worry on the corners that inevitably get cut.