Meanwhile: Back to basics.
There are 12V basics, and 110V basics.
I suggest that you start learning about electric stuff for you car/van, by looking at the 12V basics first.
It has been suggested that you start by using some AA batteries, that is a good idea. But since the goal is learning about 12V stuff, why not use a 12V battery?
At 12V it is possible to get sparks, but the voltage will not be dangerous. So you will not be injured if you touch both the positive wire and the negative wire. 12V is simply not enough volts to overcome the natural resistance of the body.
If you put 12V plus and minus directly on your tongue, you are likely to feel it, but other than that, then 12V is considered a very safe voltage level.
But what about the sparks, that still is possible at 12V?
Well, so long as you use a fuse, close to the plus side of the battery, the 12V sparks will not be dangerous!!!
So lesson one about 12V batteries: Use a fuse!!!!
Sparks happen if too many Amps suddenly run from plus to minus. Number of Amps can be limited by using a fuse.
Meaning, place a fuse as close to the plus side of a 12V battery as possible/practical, and only connect things to a 12V batter via the fuse, meaning the wire that comes out from the fuse.
When using a fuse, close to the plus of the battery, the 12V sparks will only be very short lived, as one of two things will happen.
One: The fuse will blow, and no more power (current/ampere) will flow. And this will happen very quickly.
Or Two: The capacitors (miniature batteries) in the devise you are connecting will charge in fractions of a second (causing the spark in the first place), but once charged there will no longer be a high energy flow, but only a low energy flow, and the sparks are done, and the fuse has easily survived this very short lived high energy flow.
So, when fused, the 12V sparks can be considered harmless.
You should however still not place your hands or fingers right at point of where the sparks happen, as the core of the spark itself is still very, very hot.
But when fused, nothing else, but the spark it self, will even get warm.
The second thing to know about 12V (and fuses) is:
That the fuse needs to match the thickness of the wire. Or rather the number on the fuse and the thickness of the wire needs to be matched.
Any wire will heat up, and possibly get burning hot (become a fire hazard), if too much power is being lead through it. The straight forward way to prevent over heating of a wire is, to use a suitable size fuse.
Charts that show recommended max Amp for any thickness wire, can be found many places on the internet.
Here is a link to one of them:
https://www.powerstream.com/Wire_Size.htm
The number seen on a fuse tells you how many amps the fuse will easily let through.
For example, a 20 AWG wire has a recommended limit of 11 Amps, according to the chart.
Look at the top of the chart and locate the text "AWG gauge" and the text "Maximum amps for chassis wiring"
When finding "20" in the AWG column, it will say "11" in the "Maximum amps for chassis wiring" column.
So for a 20 AWG gauge wire, one would typically use a 5A, 7.5A or 10A fuse.
Always use a fuse that is similar, or smaller, than the recommended "Maximum amps for chassis wiring" number.
Please note that I use "ampere", "amps" and "A" interchangeably. So the text "5A" is to be read as "5 ampere" or 5 amps"
Ampere/amps/A is also called current. Current basically means; how much is flowing. When talking electricity, how much electricity is flowing (the current of the electricity) is measured in ampere.
Voltage is basically the ability to flow, or how much pressure there is. Ampere is a measure for how much actual flow happens.
If needed we can revisit this at a later time. And could possibly draw parallels to water, and how water can be a different levels of pressure, resistance and flow. That are very similar to how electricity works, flows and is limited.
But back to 12V, batteries and fuses.
A car fuse will react very fast if the wire is shorted. Which is exactly the reaction we want from a fuse.
On an advanced note, it should however be known, that fuses are typically slow, especially if they are run at or just above their stamped ampere values. A blade fuse, as used in a car/van, will typically allow up to 50% more amps, for hours and hours, before it blows. And during those hours it will get quite hot.
But that is for advanced knowledge about fuses.
All we need to know for now: It is wise to over-dimension wires. Or under-dimension fuses. A 50% over/under dimension guarantees very cool wires, at all times.
So:
- fuses are placed at the power source
- fuses protect wires (and connectors) from overheating
- the number seen on the fuse tells the number of amps that a fuse will comfortably allow
- it is a wise choice to slightly over-dimension wires. Or under-dimension the fuse for any given wire gauge.
In your house, the fuse panel is what the power inlet is connected to.
The power inlet uses a very heavy gauge wire (very thick wire). If no fuses were used in the fuse panel, this same very heavy gauge would need to go to every outlet, and every outlet would need to be able to handle the max amps that goes to your house, so perhaps 200 Amp.
This is not practical. So a fuse panel is installed, close to the inlet of the big heavy power inlet.
After the fuse panel, thinner wires can be used. Because the fuses in the fuse panel will protect the thinner wires from overheating.
Same thing in a car or van.
The wire connecting to the battery is very thick, and it leads to a fuse panel in the car/van. After the fuse panel, it is possible to use thinner wires, going to every power use.
Note about Wire and Fuses for a house battery.
If you have several things being connected to your house battery, it is wise to use a large fuse very close to the battery, and then use a fuse panel to distribute power to the different devices/lamps/12V outlets that you have in your house-on-wheels.
Is this the kind of basic information you have been looking for?
Did it answer any of your questions?
Did I use too many technical words or frases?
This book/booklet might also be of interest to you:
https://www.amazon.com/Mobile-Solar-Power-Made-yourself/dp/1546567119
Just what Mike Sokol post on RVtravel magazine He also makes an argument for ground up.
