I have an RV that I just installed a Multiplus II in, along with a Cerbo-GX MKII
Both the inverter and the Cerbo appear to have built-in genset support with the Cerbo being the most fully functioned.
The generator is an Onan propane unit, it is a 3-wire unit, and the research I’ve done seems to indicate you need to build a circuit board with time delay relays and all sorts of weird stuff.
I don’t think this is the case, I think it’s way easier than that and only requires wiring it, and even that seems very simple.
The unit has a 3-wire starting system. All it does is ground the starter terminal (to start it) and ground the stop terminal (to stop it). Isn’t this as simple as it gets? Doesn’t the Cerbo natively support that right out of the box? Maybe I’m wrong, but to me it looks like you just need to run 3 wires from the genset to the Cerbo and connect them to the right place an away you go….
I suspect the generator kills the starter circuit once the unit is running as measured by oil pressure…
But, at it’s most basic, it looks like the Cerbo relay just needs to ground a pin to start it, and ground a different pin to stop it.
So is it a momentary contact to start? And a momentary contact to stop?
Or can it be engaged continuously to remin running? Or it does not matter if it (the start signal) reminds engaged when the stop signal is sent?
If anything it can be done but you will probably need to use node red for one of the signals (probably the stop). The normal gen start will work from the gui. Wired NO. And the other wired the same but with a way to detect the stop signal from the gui triggering the close of the other relay.- spit ball idea haven’t looked at it from a program perspective.
There is also the possibility of a combo of two of the three methods here.
It’s a momentary contact to start and momentary contact to stop. All it’s doing is momentarily grounding the start pin on the generator until the engine starts and then momentarily grounding the stop pin on the generator to get it to stop.
I don’t think it will matter if either are held on continuously. The generator uses an oil pressure switch to lock out the starter once it’s running so even if the device kept the start terminal grounded it should not matter. Same thing with stopping.
It should be simple, I would think…but I’m not familiar with how the relay works in the Cerbo, or how it relates to starting the genset and can’t seem to find any in-depth info on it. I have wire on hand and I’d be willing to try most anything.
Agreed, I don’t really want to buy a module when the Cerbo is already more/less a module in and of itself. Also, the multiplus looks like it would do it on it’s own.
I would have thought this was very easy “It’s a momentary contact to start and momentary contact to stop. All it’s doing is momentarily grounding the start pin on the generator until the engine starts and then momentarily grounding the stop pin on the generator to get it to stop.”
But I have no idea how the relay works in the Cerbo.
I’m guessing the reason people build out time-delay boxes is so that the start button is not held down the entire time and same with the stop button.
These look pretty cool and are very inexpensive. Basically $50 for two and they can even be had for less. Rather more sophisticated than I need but…they do look cool.
I’m quite certain the Multiplus relays will work with the assistants but I’m guessing the issue is that it’s not easy to turn the feature on or off and you lose access to all the great features in the Cerbo programming.
OGPS
(Ed @ Off-Grid Power Systems - offgridps.com)
7
This is the answer. Or, you can roll your own over three or four iterations and then realize this was the way all along.
They are either NO/NC and bi stable. So much like the k relays. The difference between all the relays is how you program/drive them logic wise really. One set through ve config, one set through node red, one set in VC.
OK, so in the cerbo, if you’re using generator start, can you still configure the relays? What I need is for it to ground one line to start the unit and ground another to stop it.
I will do this tomorrow but what I’m expecting is that the autostart will work but that it will not be able to stop the generator.
The generator is told to start by grounding the start wire on the generator and told to stop by grounding the stop wire on the generator. So the relay on the Cerbo needs to ground one wire for starting and another for stopping.
“All above Victron products and devices have a single relay; which will close when the generator needs to starts; and then expect the generator to then keep running until the relay is opened again.”
If I’m right, then starting it should be no problem but stopping it won’t work because it expects the generator to stop working the moment it removes the ground. I suspect I will need to use another relay…
OGPS
(Ed @ Off-Grid Power Systems - offgridps.com)
13
You will need a second relay and if it’s diesel, maybe (just maybe), a third. Or, you go with a generator start/stop module that has this built in along with a logic controller. The one posted above is good for most people. Atkinson Electronics sells the GSCM-WiFi which is more capable, but not needed for most RVers.
