question

k2aab avatar image
k2aab asked

Unable to set shore power above 32A

Using a Multiplus II 3000 in an ESS configuration, and using scheduled charge settings to make the most of low cost off peak power at night.

I've noticed when loads are high, charging a car for example, scheduled charge does not charge the batteries, in fact the multi inverts to help out, thus draining the batteries.

I think this is because the shore current setting has a max of 32A, when my loads go over this the multi "helps out".

A this is a ESS, and the house is fitted with a 100A fuse i want to be able to set the shore power above 32A, in VE Configure.

shorelimit32.jpg


Can this option be added to the next release?

MultiPlus Quattro Inverter Charger
shorelimit32.jpg (34.6 KiB)
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3 Answers
bathnm avatar image
bathnm answered ·

What version Multiplus do you have. There are two different transfer switch options, a 32A and a 50A. It sounds like you have a MultiPlus with a 32A transfer switch.

The product name is constructed like this:

DC Voltage / Output Power / Charge current - Transfer switch

so as an example 12/3000/120-32 is a 12v DC system, 3000W, 120A charge and 32A transfer switch.

To get 50A transfer the model needs to have a -50 at the end.

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Thanks @Bathnm I have a MultiPlus II 3000/32 so I guess this is why I'm seeing a max of 32A in my settings, battery system is 48V for info.

I'm using the Multi as part of a ESS, basically the below, apart from I'm using the CT clamp direct to the Multi rather than an ET112.

basicmulti.png

The issue is, if the Multi sees more than 32 Amps passing through the grid feed during scheduled charge, it switches to be an inverter to help out. Of cause during normal operation in an ESS I want the import from the grid to be as small as possible, but when set to scheduled charge I want it to charge, not discharge.

I think there are two fixes, both need to be changed by Victron.

  • Allow shore power setting to be increased, regardless of the inverter/charger being used.

OR

  • Change the logic where the Multi helps out if scheduled charge is enabled
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basicmulti.png (27.6 KiB)
The relays inside the MultiPlus are rated for 32A so pulling more than 32A through it can damage the relays.

Maybe you should connect some loads to AC IN instead.

Or switch to a 5000VA MultiPlus with 50A transfer relays.

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k2aab avatar image k2aab Matthias Lange - DE ♦ ·
Thank you @Matthias Lange - DE agree, but the issue I have is not so much what the Multi can handle, I just don't want it acting as an inverter at all when Scheduled Charge is set.

Potentially over night I could be charging 2 electric cars at 7kW each and also charging my 16.5kWh storage capacity at 1.7kW. With UK voltage at 240v, I could be pulling around 65A constantly plus extra load for washing machines, peeking at some 90A, so even a 5000kVA multi would still want to help out with the load.

Basically I think the logic needs to be updated so when Scheduled Charge is configured, the Multi can not act as an inverter. I believe the shore power setting is part of this logic.

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If the input current is limited at 32A, for the reasons that Matthias explained, and you are taking 40A, where would the other 8A come from if the MultiPlus did not assist? Only option remaining here is that the output is cut to prevent overload.
You wouldn't expect a 32A circuit breaker to carry 40A for very long, if you see what I mean.

You need to limit your loads, the energy sources cannot control your loads.

Now, limiting the network load is the last thing you want to do during those few golden hours of sensible rates.
So what you want to do is move the car circuits off the output of the MultiPlus and put them on normal circuits which are ahead of the MultiPlus. This way the current does not have to go through the MultiPlus, it just comes off the network directly as a "non-critical" load. This is what Matthias means by connecting the loads at the AC-IN
The MultiPlus circuit will then have plenty of capacity to charge the battery there.
The cars will take their 14kW directly from the network.

Be careful not to sail too close to the wind with your 100A fuse either, depending upon the type it may only be rated for continuous capacity at 80A. You don't want to be calling the DNO out at 4:00am.

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k2aab avatar image k2aab wkirby ♦♦ ·

Hi @WKirby I guess that's my point in a way, as far as the Multi is concerned my input is limited to 32A because of the shore power setting, but as this is a grid connected system my grid connection is limited to 100A via the way of the DNO fuse. So in in your example of pulling 40A while in normal running of the ESS I want the multi to provide 32A of the load, and the grid to top up the other 8A. And this is exactly what it does, so no problems there.

But while the ESS system is in Scheduled Charge mode I want the 40A load to be provided just from the grid, in addition I want the Multi to be charging my batteries. But what actually happens is the Multi sees the 40A draw from the grid via it's CT clamp, thinks the input limit is set to 32A (due to the shore power setting) and helps out, meaning the batteries are not charge, the exact opposite, they are drained.

I've worked out why the multi is doing what it is, and I don't expect anymore than 32A from it, it's connected to my distribution board on a 32A breaker in a T fashion via AC-IN.

I guess the shore power setting gets in the way of what I'm trying to do. If I could set the Shore Power limit to say 80Amps, it would stop the multi helping out on high loads and also charge the batteries. But I also understand why the setting is there based on the version of the multi and why you'd want this with a boat or camper van, but not with a house.

Thanks for the DNO warning too, if charging both cars, I reduce the charge limits to stop me sailing too close to the wind :)

Here is my current high level set upmulticonnection2.jpg


As you can see I just have the one distribution board so splitting the load may be difficult, but maybe something to look at.

Thank you

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Max output of MP while on grid: 32A * 240V = 7680W (7.7kW)


If you exceed this value, the MP will powerassist drawing from the batteries.


The 32A is a hard limit. The unit can't pass more than this.


7kW + 7kW + 1.7kW = 15.7kW


15.7kW > 7.7kW


As @WKirby indicated, you need to move the cars from the MP output to where they are directly powered by grid.


This isn't a "logic needs to be updated issue." This is a system design issue. Your MP is too small for what you want to do with it.

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Hi @snoobler thank you for your info. I have to disagree though re design issue. The multi works perfectly, I don't want it to provide more than 32A, I just don't want it to provide anything when it is in Scheduled Charge mode, I just want it to charge and not invert at all.

I'm using the ESS Assistant so the multi is always helping out to keep grid power draw at zero. But when scheduled charge is set in the assistant I don't want it doing any inverting, just charging. It does this perfectly, until I need to charge a car when the shore limit comes in to the equation.

When I say it's a logic problem it's because the 32A shore limit is used to tell the multi it needs to invert even when it's been asked to charge only, because it thinks the input current is 32A, when mine is actually 100A so it does not need to help out at all. Hence me wanting to set it higher to change the logic, not make the multi do something it cant.

I've added a diagram to my response to WKirby hope it helps to show how the system is configured.

Thank you

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What's connected to the AC out of the MP?
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wkirby avatar image
wkirby answered ·

Thank you so much for attaching a diagram. It gives us a lot more insight. It seems you don't have any loads on AC-OUT at all. The MultiPlus provides the loads during the day out from AC-IN.

We can also see that you have an external current sensor. Bingo.

You want this maximum value to be more than 32A?
1643321516877.png


Well, if you tick the box which says "External current sensor connected" then you can set this higher.

1643321636138.png

It's still only 50A, but it should help you out.
There is a maximum full scale measurement within the MultiPlus, so it make sense to me why it's pegged at 50A. Bigger MultiPlus units would likely be able to go higher, I'm not 100% on that though.

Otherwise, you would need to move the current sensor within the DB board and select circuits that you wouldn't want it to see. Loads placed before the sensor would not be counted, but they would not ever be powered by the MultiPlus either, so it's a bit of a balancing act.


1643321516877.png (24.2 KiB)
1643321636138.png (20.8 KiB)
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That looks like a possible bug to me! I would not trust that to always be the case. That limit should surely be to protect the MP, and if the MP only has a 32A transfer switch that is what its limit should be.


I wonder if the car charging is connected before the sensor if that would help?

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There is no current passing through the MultiPlus in the configuration that it is set up in. See diagram posted earlier.

The only current going through AC-IN will be maximum ~4A when charging and maximum ~8A when inverting. These limits are the MultiPlus' power pack limits.
The MultiPlus observes the current going through the sensor directly from the network to the loads, this current does not go via the MultiPlus AC-IN or AC-OUT terminals.

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@WKirby Perfect, I'll get this setting changed and give it a blast tonight. Really appreciate your help.
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Excellent, do let us know.

I'm going to move this question to Q&A as it isn't really a modification, it's a configuration question.

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@WKirby Sorted! I've been hacking around on this one for just over a year. It wasn't until I realised the shore power setting was causing my config issue, but couldn't get it above 32A.

Change made in VEConfig, with a bit of testing I realised I also needed to change the related setting in the ESS assistant, which I could also then be take up to 50A:

img-8524.jpg

And then success:

img-8525.jpg

Car charging and batteries charging, no more MP helping out, up to the 50A limit anyway but I can work with that.

Thank you

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img-8524.jpg (131.5 KiB)
img-8525.jpg (141.6 KiB)
Excellent, good to know it's worked out in the end.

I hope you get to keep your tariff. My Octopus Go tariff is up in 9 months time and they are going to take it off me unless I buy an EV. Like you, I'm wringing every drop I can out of my 5p rate.

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k2aab avatar image k2aab wkirby ♦♦ ·

By luck more than judgment I fixed for two years with EDF with a economy 7 tariff of 8p so good till July 2023. Before then I'm planning to build a garden shed/office and roof it in PV and connect up to a MPPT RS. I also want to re roof the house to make room for some more panels and connect them to the other string on the RS. If only work did not get in the way of the DIY projects.

I've just upgraded the storage from 6.5kWh to 16kWh, hence me wanting to get the most of of those 7 hours. Currently run at about 71% night units, hope to get this up to 90% with the extra capacity.

Thanks again

Andrew

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Octopus Go gives me just 4 hours, so I really have to get the hammer down during that time, yet I only have a 60A fuse. I'm peaking at 30A now so a 7kW EV charger on top of that would tip me over the edge.

I have 4kW of PV dotted about the place, I already have an outdoor office which is covered with PV :)
House roof could do with PV and it's SSW facing, but I'd do well to have the roof inspected first. Just need to decide if I get a regular grid tied setup, or just go DC coupled with a RS. FIT's are rubbish these days, so self consumption makes the most sense to me.

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neki avatar image
neki answered ·

What you need that in x time mp goes to charger only mode. Maybe you can do that whit pbc, and some raleys/ timers. I dont know what you have in system, gx or not and is it possible to play whit remote or not.


But what I can see you need switch between inverter and charger only and maybe your solution is on that, not to put softwer limits over hardwer limit


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