I think it would be classed as a battery. If we take this sunsynk one as an example, it has 16 lifepo4 cells in series totalling 52v nominal, an internal BMS and ports at the bottom for communication with the inverter and for paralleling with another battery. It requires an external fuse or MCB and it’s in a metal case that requires earthing.

If I’m not mistaken, monoblocs are usually those leisure style batteries or perhaps even the cells themselves?

Akbar Ramzan said:

Ok, yes that is ideal but what about the majority of existing batteries which require external overcurrent protection as per manufacturers instructions?

Also a thought ... I can buy an mcb separately, but that doesn't mean it's correct to install it on a din-rail simply screwed to the wall. I know I need an enclosure for that ... same goes for monoblocs?

Though I see what you mean by the tool-free removability of the battery connectors. They can just be unlocked and pulled out

Whilst most leisure batteries are monoblocs, some popular EESS batteries are too, despite them having a metal casing.

Basically, if it's intended to series/parallel and it's got no internal overcurrent protection, it's probably a monobloc (unless of course we are talking about individual cells).

So you’re implying that these “monoblocs” should be installed into another enclosure which prevents the user from being able to access the battery connectors without a tool and ensure the cable between the battery and the MCB is inaccessible and protected.

that seems sensible but I don’t think I have seen many installs which do that. I have seen rack mount batteries with a lockable door though.

Akbar Ramzan said:

So you’re implying that these “monoblocs” should be installed into another enclosure which prevents the user from being able to access the battery connectors without a tool and ensure the cable between the battery and the MCB is inaccessible and protected.

That's my feeling. Ordinary persons and children should not have access to DC connectors for the levels of current we are talking about, that can be removed on-load without a tool, unless of course we are talking about a plug and socket-outlet combination to an appropriate standard for use by ordinary persons, specifically made to be capable of being disconnected safely on-load.

Akbar Ramzan said:

don’t think I have seen many installs which do that. I have seen rack mount batteries with a lockable door though.

There are alternative solutions, sometimes even from the same battery manufacturer. I have definitely seen solutions available with batteries in a metal enclosure that also contain the overcurrent protection, provided as a complete package. One manufacturer of a popular "monobloc" solution with rack, also has the "complete package" option, available as a "bolt-together" expandable set with inbuilt overcurrent protection.