question

@snoobler Thank you for that response.

Interesting on that "DC Power" - it's not in the Cerbo GX docs but googling around I do see that there's an enable / disable setting. The SmartShunt is across my entire boat ground so there shouldn't be any phantom loads - I bet my installer disabled it.

But I do want to display a second battery. The docs only say "Double M8 battery plus/minus connection" and "M8 bolts (2 plus and 2 minus connections)" so it wasn't clear to me they were the same battery. The docs also have this passage:

"Two DC outputs for charging two batteries The main DC terminal can supply the full output current. The second output, intended for charging a starter battery, is limited to 4A and has a slightly lower output voltage."

So...yes, I'd like to add a "starter battery" and have it show up on the Color / HTML displays or output appropriate NMEA 2000 PGNs. What is the standard method for doing that?

Thank you also for commenting on my generator autostart issue - I had come to the same conclusion that I needed an additional controller like a Magnum MEAGSS (or cruft up my own) for that feature. It's probably not worth it - but I would like to see the Generator show up on the Color / HTML display. Is there a method for displaying that? I see some of the configurations on the VRM portal have a Generator:

DC Power is enabled when your system has DC loads, and you want to track them. Otherwise, they just go into a black hole of sorts. I don't have any DC loads, but my DC consumption is always higher than my AC consumption. This is mostly the idle power of the inverter and other equipment.

Hopefully, you came across this:

https://community.victronenergy.com/questions/72369/what-is-dc-power-on-vrm-dashboard.html

In your initial post, you've correctly circled the (+) for the starter battery. The (-) attaches to the primary (-).

The GX is not for displaying everything you have, but for displaying everything in the Victron ecosystem. If your generator AC out is connected to the AC input of the MP, then it can be displayed when running. If it's not connected, the GX has no means of telling what the generator is doing. Here's my VRM display:

When the generator is feeding power into the inverter/charge, I get a number in the Generator box. If it's charging, the "Inverting" will display the charge phase (Bulk, absorp, float).

Is your generator AC output connected to the AC input of the MP?

Again, what is the purpose for the 3rd battery, and why do you want it to display on the GX when it's not really a part of the system?

Thank you again @snoobler! Truly appreciate the help - and today is my birthday so it's a great start. :)

I had seen that post - and read that passage in the Cerbo docs but reading it again, I think I need to turn "Has DC System" to "yes". The wording was confusing..."Enable this for boats, vehicles and installations with DC loads and chargers - in addition to Multi and MPPT chargers" - it's not clear what "and" means there - I don't have a charger in addition to the Multi. I suspect it should be "or".

Being a boat, I have substantial DC loads - so I can see that enabling that would give me an equivalent of the DC Amps meter on my panel, with the rest of the discharge via the SmartShunt going to the inverter. It ALL goes through the shared ground that the SmartShunt is across.

I'm pretty sure my generator does go through the Multi (have not tried that yet) - but these boats came with a panel transfer switch:

I suspect that the output of this transfer switch is what goes to the Multi. I only see one set of AC inputs on the Multi - scrolling up you can see the image that shows both "AC Input' and "Generator" into the Multi - how is that wired with only one set of AC inputs?

Which leads me to "co-supply" with PowerAssist. The Multi would need to know what's coming from the generator separate from Grid. That lead me to this thread: Easy Solar II - Power assist - required current sensors - Victron Community (victronenergy.com) where...let's be honest...confusion reigns. :)

I don't need PowerAssist - but I would like to distinguish between power coming from the Grid and generator.

You asked about my 3rd battery. I probably confused things with my discussion of my battery configuration - but it's common on a boat to have two banks: one for loads, and the other for starting engines. I have effectively combined them, but I'd now like to add a battery to start the generator (aka "starter battery") and have it appear on the display.

Searching doesn't get me to exactly that, but this is close: https://community.victronenergy.com/questions/83577/starter-battery-voltage-monitoring-with-isolated-s.html. While it would be nice if the Multi reported what was going to that "starter battery" it looks like I'm going to need another SmartShunt connected to the Cerbo - does that sound right?

Happy belated birthday!

If you have loads pulled directly from the battery besides the inverter, yes, you should have DC loads enabled. In my case, my systems are in series. I have DC loads, but they are provided by batteries/converters powered by AC from the inverter. Not efficient, but I don't have to rewire the RV - just plug into my off-grid "shore" power system.

The MP does not have dual AC inputs. The Quattro does, but even with the convenience of the two connections, only ONE can be active at any time. Your transfer switch appears to permit only one system active at a time, though I can't tell how it works from the picture.

AC Input and Generator are just the display. It tells you at a glance WHAT is providing the AC input. They would never be active at the same time as that could be catastrophic, and they shouldn't be unless they are completely isolated from one another on different systems, e.g., the grid is powering the MP/boat and the generator charging the starter bank where the generator/starter bank are connected to nothing else. Not efficient, but it's a situation I could imagine.

Thus, there is no need to distinguish the difference between grid and generator input as they shouldn't be active at the same time. The MP can only know that SOMETHING is providing AC input.

PowerAssist is only for weak AC input, e.g., let's say your shore power is limited to 15A. If your boat pulls more than 15A, the MP would supplement the shore power with AC power from batteries to prevent the shore breaker from overloading.

Note that the ambiguity in that thread has been resolved. For simple PowerAssist, an external sensor is NOT required.

I'm not 100% on this, but even with the addition of the BMV on the starter battery, it will not readily display on VRM or the console. A device is flagged as the shared voltage/current/temperature source, and THAT device is what's displayed on VRM Dashboard/Console.

You can display it in Advanced widgets.

IMHO, way more trouble than it's worth.

@snoobler and thank you again! And thanks for staying with this thread as it drifts when I discover a new capability (spoiler alert: "Detect generator at AC input" coming below).

I was able to get to my boat yesterday and turn on both "Generator" (AC Input 2) and "DC Power" in the Cerbo - and in my limited experimenting the DC Power was extremely accurate and sensitive. Turn on one LED light and it goes up a few watts - turn off and it goes back to original. Power up the electronics and same thing. So it is analogous to my DC panel ammeter but it includes things that don't go through that panel (furnace, bilge pumps) and it's way more accurate. Hugely pleased with that.

AC Input 2 says "Note additional configuration is required for complete setup of these options" but doesn't have a pointer...and then I found this "Quattro has mains/grid electricity connected to its AC-in 1 terminal, and a Genset connected to its AC-in 2 terminal. With this option enabled, the Genset will only start after a mains failure". I don't have a Quattro :)

And I wasn't thinking clearly on PowerAssist - thank you for clarifying. The use case I had in mind was if I lost shorepower at my slip the generator could start and take over. That is something that has happened maybe twice in more than 30 years so...yeah I'm going to let that go.

Even without generator auto-start the setting "Detect generator at AC input" gave me hope that the Multi could indeed detect whether the power was coming from a generator versus mains - if I shifted that lockout breaker on my panel. But the auto start docs give more information: "Enabling this feature will raise an alarm on the GX device, as well as trigger an alarm email from the VRM portal(1), whenever power is not detected at the AC input terminal of the Inverter/Charger."

I think my next step is to manually start the generator - throw the lockout breaker - and make sure that the the Multi "accepts" the input from the generator.

DC loads is the leftover of what the system can't account for in AC loads. Individual changes should be very accurate, i.e., a 10W light should increase it by 10W, but the TOTAL amount is just the leftover. It does include things like the inverter's self-consumption, inverter inefficiency and any other DC used by BMV, MPPT or GX.

Yep. AC-in 2 is just for the Quattro.

Agree with your next step. Would be good to know that the MP can properly accept the generator input. That way the generator is powering everything the MP would normally power while "off-grid" and charge the MP batteries. Just make sure shore and generator can't be active at once! :)