I have Multiplus II, 150/70 MPPT and non Victron lifepo battery. I want to build an install and forget off-grid system. How is charging handled with multiple inputs. Ideally I would like solar to be always first priority and Multiplus add to that until some charge amount, lets say 60A is filled. But atleast make sure that AC and solar don't add up to amp levels that are harmful to battery.
Is this possible and do I need to buy some additional equipment for it?
Yes, a GX device where you can cap the system wide amps in DVCC to the battery and it can make sure each component does its share.
Hi @pekkaj
Usually in a simple system (non-ESS), priority to solar can be arranged by having the charge V parameters of the Multi set slightly lower than the mppt. How you do this depends on whether it's a genset or grid, as they each have different needs. Like you might decide to just bleed in grid slowly, but a genset you may want to maximize it's output to reduce runtime.
But I agree with Alexandra, a GX device like a Cerbo would be a great addition, and you shouldn't need anything else. It will give you access to all settings via VRM (with www). A Win pc is a good access tool if you happen to have one.
You say "install and forget", but be warned, the options a GX opens up can be addictive.. :)
I don't have access to Multiplus setup yet but came up with an idea. Would it be possible switch Multiplus AC input on with BMV-712 relay? When solar is plenty, do not use AC, but when voltage drops to certain level, Multiplus AC input kicks in.
That's an option, but bear in mind the BMV can't switch AC directly, so you'd need an added external AC relay, then devise a way for the BMV to switch that. There's already an ACIn relay inside the Multi that can do this, and logic to drive it, but you've no access. An MK3/usb adaptor would be a cheaper option than a GX for access.
But you haven't really told us much. You say you're "offgrid", but have external ac available? So maybe you want to be offgrid?
What I'd do in a case like that is have AC off as standard mode, and switched on only when needed. Like with low SOC, and/or High Load and/or Low V. No good starting a solar day with full batts, hey? This is all possible, but to do it properly the GX is the ultimate. Things like just to get the BMV's SOC across to where it can be used is an issue without it.
I have Multiplus, mppt, lifepo4 battery and bmv-712 and would like to use it off grid as much as possible, only backup AC on rainy days. I have external AC available.
Okay so Multiplus can prioritize battery over AC on it's own? Then as you said, I need MK3-USB or gerbo to program Multiplus settings?
I was thinking that BMV could control Multiplus with the relay, but it makes no sense if Multiplus has the functionality built-in.
I have read the manuals and still don't have the information how to make multiplus to use battery until its low and then switch to ac? Preferably multiplus should be in more quiet inverter only mode and switch to loud ac charging mode only when needed. Should I configure multiplus with mk3 adapter or buy gerbo to do the switch? Or could bmv-712 relay be used as a switch?
https://www.victronenergy.com/live/assistants:ignore_ac_input_using_the_generator_assistant
This isn't a great example, as it's confused with an ac-coupled application. But there's Assistants and also Virtual Switch in there to do this. Usually under the VEConfigure (software) umbrella.. https://www.victronenergy.com/media/pg/VEConfigure_Manual/en/assistants.html
You have somewhat of a learning curve to traverse here, so you'll need to be patient with your research. The Victron website has masses of stuff once you know what you're looking for.
The MK3 is the bare minimum, the Cerbo fully-featured. I suspect in the washup you'll want the Cerbo.
I found the answer here: https://youtu.be/sbLREfC7ocU
So use Virtual Switch / Ignore AC and add exception "do not ignore AC" when power level is below threshold value.
