question

gabius avatar image
gabius asked

Wrong AC in reading MP2

Hello guys, i'm facing issues with my ACin reading ( amp vs watts doesn't seems to be possible)

I Have : Multiplus 2

Cerbo GX

Mppt smart solar

Any of you have the same mesurements or my mp2 has a bad energx metter ?

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Multiplus-IIESSEnergy Meter
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Juraj Nikolov avatar image Juraj Nikolov commented ·

@Gabius Hi, I have the same problem as you, it's similar on AC Out too :) you definitely have it too if you look better :) ... what I noticed on other forums, other people have it too and never thought of it U * I mean in this case unequal W :P

I would understand a deviation of 20~40W, but 179W is already quite a lot, paradoxically higher demand = higher difference... so what does it actually push the VRM to, what data??? What is real data???

I have one MPII that I sent for a claim for this purpose, so far I have replaced it with a brand new one :) it worked exactly for about 30 seconds before it started showing nonsense, but those 30 seconds were CORRECTLY MEASURED.. ammeter at the output and input.

They even posted it as a bug:

https://community.victronenergy.com/storage/attachments/41748-2021-12-mpii-esii-quaii-current-sense-socket-issue.pdf

Paradoxically, the new MPIIs no longer have a 3.5 jack :D so the instruction how to fix it... I think it didn't work :P but I disconnected the terminals and connected it is basically the same procedure as with the jack... erm it didn't help :D what a surprise :D



@Guy Stewart (Victron Community Manager) @Alexandra @mvader (Victron Energy)

I would greatly appreciate it if someone from Victron or experienced members could describe how it actually measures and what it actually measures.

Such improvements as the solar profit forecast are also encouraging :D but that's probably is for two things, if it shows people nonsense, sorry wrong data :)



AC IN 244 x (-1.4) = -341.6 aprox. 10x more :D BUT -1.4A is freezed value…

AC Out 244 x 1.8 = 439.2 … also diferecne only 273W :P

I ask WHY … ??? … how to explain that for customers ??? Logicaly, Matematicaly :D :D :D Sorry…



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1 Answer
Alexandra avatar image
Alexandra answered ·

@Gabius

@Juraj Nikolov

V * A is a very simple way of looking at power, but in a circuit there is also R....

And then there is power factor. There are bunch of things in your systems that do most likely have poor power factor. Led lights can be a major one. E.g a 7w led light with 0.5 PF actually draws 14W. Just the volt amps are out of sync.

So deeper elctrical maths and electronic circuit equations can (cos phi etc) explain alot more.

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Alexandra avatar image Alexandra ♦ commented ·
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Juraj Nikolov avatar image Juraj Nikolov Alexandra ♦ commented ·

@Alexandra


OK, let's try another way please :P


1) why, if I disable the system from ESS and put it in OffGrid mode, does AC-out 1 show (and I also measure) the same and correct values (U*I=W :P )?


2) if I include the MPII in the grid under Ve.Config GridCode: Europe +ESS ...

So it starts doing what I describe. + before the firmware update I had v.496, I updated it to v.502 no change... besides that it showed and measured stupid things, GX was freezing so that it was not possible to get through IP web or ssl to GX :) + it discharged the batteries into the grid 4kw , then started charging them from the grid 4kw, regardless of whether ESS mode without batteryLife or batteryLife was set, it did this mainly if the Grid point was 0 or -#; grid feed-in was sett as - off .

After the MPII upgrade to 505, it stopped freezing, but the VMR also crashes further, but significantly less, even with a completely new converter :)

With the new inverter, as I wrote, after the first start, the first 30 seconds showed the correct values, even the same as I measured with a clamp ampmeter... I really don't know how to explain this. I have no reason to invent.


Was it also caused by the power factor? : ) I do not think so :)

If yes, how to sett the system at it show correct values ?

Becouse if I measure at AC-out some else what show MP how I can trust that it show correctly ? The same on AC-in :)

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Thanks for discussion

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Alexandra avatar image Alexandra ♦ Juraj Nikolov commented ·

So you have an entirely different problem it seems.

The inverter does not claim to be a measuring instrument. A digital multimeter is not the best way to measure power with the accuracy you are trying to do it. A clamp meter even held at an incorrect angle can manipulate the result.

A quality power logger is the correct instrument in this case.

If you notice even the htz are slightly different which is why I am saying you cannot use volts x amps (which is high school maths) to explain the watts. It is way more complex than that.

If you go offgrid another possible answer can be electrical 'noise' from the grid interfering with readings by the inverter. Again a power logger would tell. Not a volt amp reading.

You could have a problem between neutral and earth somehere. Or some other kind of wiring issue. That kind of change between on and offgrid definitely points in that (wiring and electrical interferance) direction.

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Juraj Nikolov avatar image Juraj Nikolov Alexandra ♦ commented ·

if I set grid in ve.conf it show measured data corect.

Or if I set under GX - Multiplus - mode "invert" also it show corect measured data ... : )

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This doesn't happen in offgrid mode, or when I change the inverter mode to invert only... I believe it's because it's measuring crap and the system is freaking out :P

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Alexandra avatar image Alexandra ♦ Juraj Nikolov commented ·

If you disconnect from grid and the problem goes away, it is being injected into the system from the grid. Either in the form of noise. Or in the wiring leading up to your inverter. Neither of which i can help you with from here.


Since when it inverters the problem goes away. You have established that the inverter is ok.

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Juraj Nikolov avatar image Juraj Nikolov Alexandra ♦ commented ·

@Alexandra

Ok, I'll try to change the wiring so, that induction can't occur :) ... if that doesn't help, I'll use the AC-in only as a source for the MPII if get over 4kw, I think it's solved via HUB4? When ESS doesn't work :)

Anyway, thanks for the inspiration and help; )

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Alexandra avatar image Alexandra ♦ Juraj Nikolov commented ·

You there are many ways besides ESS to prioritize self consumption. When the grid is problem.

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Juraj Nikolov avatar image Juraj Nikolov Alexandra ♦ commented ·

@Alexandra

It is enough for me if I can function like this:


AC-in would be connected only if the consumption of the inverter exceeded 4kw (4kw would be supplied by the inverter and everything over would be drawn parallel from the grid), if the consumption dropped to 3.5kw, it would disconnect from the grid (only the inverter would take the load). It would be perfect if I didn't send even 1W to the grid :) even if I can (it's completely useless for me to load the converter)


If I could solve it through these settings, then great.

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And this seem to be only for AC coupling

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Are there other possibilities? : )


Thanks.

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Juraj Nikolov avatar image Juraj Nikolov Alexandra ♦ commented ·

@Alexandra I tried to measure with ET340 and CRT100550 and it measured exactly the same as a clamp ammeter... I tried to measure in the conditions I have to and confirm measuring it as best I could :)


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and very similar problem if not the same:

https://community.victronenergy.com/storage/attachments/41748-2021-12-mpii-esii-quaii-current-sense-socket-issue.pdf


and frequencie is oscilating 49.9 - 50.1 Hz Thats after hard reset GX :)

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gabius avatar image gabius Juraj Nikolov commented ·
Same issue for me, they thought it’s cause of my bad settings, but no one manage to found what was « flasly configured »…
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Juraj Nikolov avatar image Juraj Nikolov gabius commented ·

@Gabius

Hi,
I noticed one or rather two things today :P
1) when ESS charges the battery to 100% and I have it on, then min. from -1000W it shows the correct values (U I W Hz), I didn't have time to pay much attention to it today. I will look for the value from which it shows and measures correctly :) AC-out did not show the current correctly, but I know that when my appliances work (I was off the grid for a year), what is their approximate consumption or it hasn't changed, so it measures as a result + - AutoBus ok :)

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2) When it sends it to the network from -300W, the MPII shows nonsense from the current point of view.
So this is purely a SW error or the developer has ******* on fine-tuning... :) it looks more likely :D
If the Chinese can do it in their products.... why Victron not ??? :D

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