[ThosD]

I got this reply from another forum:

Standards over the years migrated to never disconnecting “ground” for safety & consistency, and not just in car batteries.


Some reasons:
The idea/message of disconnecting power source at the “0V” side is counter-intuitive, and in some cases dangerous.
ex: is disconnect connector fully insulated (since some parts are always live)? 0V connections are seldom insulated, while power i.e. 12V or 6V usually are.
Newer systems cover the “hot” terminals.


Ground leads are often physically harder to connect to in some cases- i.e. braid, straps, metal rods or in a tight space, vs. insulated wire coming off the “hot” side, to a switch that can be located elsewhere (with insulated connector cover)


Not saying a model A has any of those situations.


Motorhomes using multiple +12V batteries for vehicle starting, house or other aux battery banks always disconnect +, usually with a big knife switch. Some are more sophisticated and have shared power mgmt between all.