despte an isolation switch being used when we are parked up

Is the isolator a manual switch or does it work automagically ("split charger", relay, diode isolator, dc-dc, etc)?

If the leisure and starter batteries really are isolated then it's a chassis problem. The classical approach is to youtube.com/watch?v=G7BvKNfY6h… and pull chassis fuses until the current stops -- that circuit is the problem.

occasional drain of the motor batteries

How long does it take for this to happen? A day? A month? If you have solar on the rig you could leverage it to keep the starter battery[s] charged. This would also work if you are on shore power while parked up.

something is going on

Parasitic drains can be frustratingly hard to find, so don't be discouraged if you don't find it right away. I had a '72 beetle with a slow drain. Took me weeks to find it -- it was the original AM radio, which I never listened to. The volume knob was turned just far enough to power the radio on but not far enough to make any sound. Argggh!

We dont have shore power connection as such because everything is 12v.

Shore power can be used as-is (120v, 240v, whatever the local standard is) especially on larger RVs. On vans it usually feeds a converter/charger that run 12v loads and charge 12v banks.

Minecraft?

github.com/Lodestone-Team/lode…

GitHub - Lodestone-Team/lodestone: A free, open source server hosting tool for Minecraft and other multiplayer games

A free, open source server hosting tool for Minecraft and other multiplayer games - Lodestone-Team/lodestone

^GitHub

A Minecraft server is the classic.

Don't discount just putting together a basic webpage that can be accessed at home too- something he could put together in a basic HTML editor (drag and drop) and put his favorite things on or whatever he may be focusing on (cars, animals, space, you name it).

I showed interest at around this age and my dad showed me CentOS and building basic webpages. I didn't take too much interest in that, but I asked him if we could build a Counter Strike server and he obliged. He's a nerd himself so we had a static IP for the server and everything. Worked well!

Anyway, I would recommend getting an old desktop and installing Ubuntu server or desktop edition with a desktop environment. Show him how to navigate the command line and what that means if you follow the file explorer at the same time. And then hosting very basic things(webpages, local game servers, etc.).

He might really latch onto it, or might not be interested whatsoever. I latched onto it, ended up building my own PCs soon after, and have my own homelab and I work as a full time Linux sysadmin now.

Minecraft server. Then Pufferpanel, then modding. Tons to learn.

Put it in a VM for him and take snapshots for easy recovery.

Hedy is an open source programming language that is broken into levels for easy learning. As you progress the language gains more capabilities, so they are never overwhelmed with too much

In contrast to block based languages like scratch its goal is to leave students ready to switch to Python by the end.

Each level has small tasks to complete so you can tackle it piece by piece and get a sense of progression.

hedy.org/

I think educational activities work best once they have some application to someones life. So it'd be something within the realm of a 7yo. And it's not fun unless there's a sense of achievement every now and then, along with all the stuff to learn. So probably not too steep of a learning curve.

Sadly they discontinued Lego Mindstorms. I think robotics is a great hands-on topic. People can grasp what they're currently doing, why they do it, and what it's good for. It has a tactile aspect, so you'll train dexterity as well and gently connect the physical realm with the maths.

But other than that, I bet there's a lot of things you can try. Design a website (and deploy a small webserver). Maybe some easy to use photo gallery if they have a tablet or camera. Maybe a Wordpress for them to write a Blog? They should be familiar with the concept of a diary. Kids love Minecraft, so maybe a Luanti server if you're into Free Software. But learn how to add NPCs and animals, that is (or used to be?) a complicated process in Luanti and the world feels boring and empty without. A chat server to their loved ones could motivate them to read and write text (messages). Or skip the selfhosting aspect and do the kids games available for Linux. Paint, LibreOffice...

I like the recommendations from other people as well. Sadly I don't know which kids programming language works best. I think I heard you can just go straight for Python as well. Not sure if that's true or what age group that applies to. It's a bit more involved to learn the syntax and why you need brackets around certain things etc but at least they get to learn the real deal and something properly useful. 7 might be a bit young, though. And there might be a language barrier. But that applies to all the computer stuff behind the scenes, unless you're a native English speaker.

I'd argue home assistant with some smart LEDs and a few sensors would be great.

Having a bulb that let's you know the outside temperature/weather when you're getting dressed in the morning is neat. Having a dimming pattern for sleeping time. Tons of other really simple stuff available too.

I do not recommend using a seven year old as a server for the following reasons.

1. their parents will get mad
2. the neighbors might call the police about all the children you have racked in your basement
3. they have poor computing power, wait until they're at least in their late teens (although software updates come too late and the system is usually very unstable at that time.)
4. think of the smell! your house will smell like a kindergarten
5. food costs are already high enough, add two or four growing kids to that budget and it's far cheaper to run a couple Dell R610s every month.

overall, not worth it mate. good luck though!