question

@douglane The link gives me different scenarios!

That said, from my understanding both scenarios in your post are correct. They are just doing different things, because of the inverter verses inverter/charger.

When designing you need to remember that nearly all FET based systems, can only allow current to flow in one direction, in this case from the battery to the System + port. Therefore connecting a charge source to System + will create no end of problems.

In the first example in your post, their is a simple invert, as it is just a load source it can be connected to the system + port. In a load disconnect situation the system + port is disconnected and the inverter would just stop working as it has no supply.

In the second example in your post, it is an inverter/charger. Due to it's charging nature it CAN NOT be connected to the System +, as that is just for loads. It is therefore connected direct to the battery, this way it can be a load and a charger. Therefore how does it get signalled to stop charge or inverting based on the BMS. This is teh extra signal wires depicted. One will signal the Inverter/Charger that it should not provide any charge, the other is to signal a load disconnect. You additionally need to install assistances on the Multiplus, to watch for these signals and control the inverter/charger accordingly.

Regarding MPPT, your figure 1 is very clear. The MPPT is connected direct to the battery (as it is a charge source) and the charge disconnect from the BMS wired to the MPPT. This will signal it to shut down on a charge disconnect.

I can not remember, but I believe (so please do check documentation) that the charge disconnect is feed from the Cerbo to the MPPT over VE.Direct if and only if there is an inverter with the two wire BMS assistant installed. If this is not the case then what you can do is take a Smart Battery Protect; connect the MPPT to the supply side and the battery to the load side. Then connect the SBP load disconnect to the BMS charge disconnect. This then frees up teh VE.Direct port to wire to the Cerbo and the BMS will signal the SBP to stop passing current on a charge disconnect. When the SBP disconnects the MPPT will detect this and stop charging. This would be my preferred choice over relying on the Cerbo, as there are two many things that could cause a charge disconnect when not required, such as the inverter being switched off.

Which product and wiring topology to use, comes down to the products selected and what you are trying to achieve.

Hope that all makes sense and helps.

@Bathnm On review, I'm not sure that your assessment is correct, at least based on my read of the manual for the Smart BMS 12/200. In all the examples the documentation refers to a Multiplus, which is by definition an inverter/charger. Also, in section 6, it specifically states in the specifications that the System+ max discharge current AND charge current is 200 Amps. That would seem to indicate you can charge via the System + port as long as your total charge current is under 200 Amps. Here is the excerpt:

I thought I'd add some additional detail about my installation experience as there is very little information about the Smart BMS 12/200 out there, and the manual does not explain the reasons behind the different options for connecting loads and charging sources.

In the end, I connected my Multiplus Compact 12/1600/70, my Smart Solar 100/30 MPPT, and all of my DC loads directly to the System+ port. The System+ port supports up to 200A charge/discharge current (peak 400A), and if your system fits these requirements, this is the simplest setup. The System+ port independently switches off charge sources and loads when the voltage or temp of the batteries is too low or too high. This means that you do not need to buy a Battery Protect to control your DC loads or charge sources, and you do not need to connect control cables to your MPPT or Multiplus. This significantly reduces cost and complexity, and is a big selling point of the Smart BMS 12/200 over the Smart BMS CL 12/100 which does not have a System+ port.

If your inverter, charger, or loads exceed 200A continuous, then you also have the flexibility of controlling some or all of your loads or charging sources (except for the alternator) directly to the battery rather than the Smart BMS 12/200, and using remote cables to control them. This gives you a ton of flexibility, but it could certainly be better explained in the manual!

I have included a diagram of my install in case it helps anyone, or someone wants to pick it apart :-)