I know a lot people with high end ICE installs, fit second batteries, to power the amps etc

As part of my besoke dog ventilation/comfort system, I've always powered it from a second leisure battery. Which is split charged with the main battery, from the alternator. Whilst the circuit shares a common earth, the ventfan, heaters etc, have always been an isolated from the cars electrical system.

The leisure battery is an AGM type: whereas the main battery is of course, a Silver Calcium type

As I've not had a vehicle with CANBUS before, will this cause any unforeseen problems?

Also, what are those quick release charging connectors (plug and socket) called, that ambulances and paramedic vehicles have? The ones that eject the plug , when you turn on the ignition? I quite like the idea of fitting one, as a back-up charger device for the second battery.

Kussmaul auto ejects (but there are probably a few manufacturers). I'm not sure if you can use them with a DC charger or if you'll need to installed an AC charger in your car.

I don't foresee any issue with split charging a battery, as long as the charging system doesn't output too high a voltage (along with ensuring you have the correct relays to connect and cut off the secondary battery when charging, and to not drain the vehicle battery).

Thanks Micro :)

I shall go googling

Each time, I rebuild the dog ventilation/comfort system, I keep adding more modifications to it!

The comparability should not have an issue, as the voltage is running to the fan and not the rest of the car.