question

pedaaa avatar image
pedaaa asked

ESS Multiplus with EM24 slow response also on AC-Out?

Hello,

i am planning for an installation with 3x5kVA Multiplus II with EM24 grid meter and loads on AC-in as well as on AC-out. Like this:

1644312702824.png


I came across these threads, where users notice quite slow response to loads, if the ET112 grid meter is installed:

https://community.victronenergy.com/questions/51697/victron-ess-et112-slow-response.html

https://community.victronenergy.com/questions/44996/multiplus-ii-et112-current-transformer.html


I have some questions to this:

One suggested solution was to place the loads behind the Multiplus II at AC-out1 and AC-out2.

OK, thats not a problem. All my loads, that would require fast response would be connected to AC-out anyhow. So.... does it mean, with EM24 connected and set as grid-meter, the loads on AC-in will be handled slower, but the loads on AC-out STILL would be handled fast?


OR.... will all loads be handled slower, once a EM24 grid meter is installed? regardless if connected to AC-out or AC-in??


Some more detail questions:

1. Will the EM24 Ethernet or EM24 RS485 version work better for having faster response? Or is there no difference?

2. Is it better for faster response to have an external Cerbo GX or instead better use a Multiplus II with internal GX?


hope you can help to clarify!

many thanks!!

Peter

Multiplus-IIem24
1644312702824.png (39.0 KiB)
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7 Answers
Paul avatar image
Paul answered ·

I just installed one MPII 5000 together with a Cerbo and EM24 and have chosen the ethernet version (modbus over ethernet).

If I would have to do some nitpicking, the ethernet version looks faster to me than the RS485 version because the latter communicates over a 9600 baud connection where the modbus over ethernet communication goes faster?


My advise would always be: go with an external Cerbo, which gives you a lot more flexibility if a device fails.



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pedaaa avatar image
pedaaa answered ·

Hello Paul,

my idea on the internal Multi-GX was, that it has the faster CPU than Cerbo GX. Maybe this does help in that matter?! Or will this not have any effect on load response times??

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Paul avatar image
Paul answered ·

@Pedaaa More horsepower in a CPU doesn't always improve:

In 1985, Lotus123 (yeah I know, that was looong time ago and before Excel took over the market) was running from a floppydisk of 720kByte and took less than 500kByte. It run smooth on a Intel 75MHz machine with only 2 MB memory.

Now we have Excel with a barking dog as an assistant and a lovely visual style.Together with the rest of the Office suite it takes 4GB! And you need at least a 2GHz CPU with 8GB of memory.

90% of the jobs can still be done with Lotus123 however, people are used with fancy interfaces.

What I want to make clear: a good programmed piece of machinecode on a restricted piece of hardware can do it's work more reliable and faster than a crappy written software on a faster system :-).

From the redundancy point of view: If your MP fails, you can still see values from the batteries when looking at the portal.


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pedaaa avatar image
pedaaa answered ·

ok, but do you also have ideas regarding the "slow response" and AC-in vs AC-out questions?!


and do you know, that EM24 RS485 would cause slower load respones than Em24 Ethernet or is this just your thought?


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Paul avatar image
Paul answered ·

My system with ethernet energymeter reacts very fast, changes are instantly

But I have no reference then my gut feeling

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Paul avatar image
Paul answered ·

and some years of technical experience, if that counts :-)

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pedaaa avatar image
pedaaa answered ·

have you read through the initially posted links?!


They say and proof, that there is a significant response time difference, if using grid meter vs. using CT-Sensor or no external meter.

And it does make a difference if the loads are connected to AC-in or AC-out.

I only wanted to know more specific which configurations exactly trigger this "slowed down response time" behaviour?!


So, if you have no reference... or have not tried different configurations, How could you tell anyting about differences?! Sorry, this would not answer the questions



3 comments
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Jay avatar image Jay commented ·
Did you manage to track down how to speed up response or what is the best config to get fastest response using ET112 on a Quattro/Multi?
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andy156 avatar image andy156 commented ·
From reading around it seems the grid setting can make a difference as well. I do wish there was more detail. on this for decision making. 10-15 seconds to settle with an external meter is not fantastic when it runs more or less instantly without the ET112/EM24
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larsea-dk avatar image larsea-dk andy156 commented ·
I can also confirm that the EM24 and the Multiplus is very slow to respond to MPPT power. For me this is quite an issue, since this has given a lot of over voltage alarms on my battery due to MP2 slow at ramping up. Of course ramping down is also slow, which do discharge the battery....but at least not destroying my battery due to over charge!

I have read that the limit is in firmware and related to grid code. I have heard 400w/s. I cant see the reason. Can the system run without a grid code?

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Related Resources

MultiPlus-II Product page 

MultiPlus-II Manual

MultiPlus-II 230V Datasheet 

VE.Bus Error codes

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