question

scraggs avatar image
scraggs asked

Input watts incorrect

Hi all
I have been charging my off grid battery setup today and have noticed that the watts used via VRM and connect is around 700 watts under what is actually being used.
Setup is 930a/h traction battery, multiplus 2 48/8000 and smartshunt 500, there will eventually be 14kw of PV connected.

I have searched but can't find an answer.
Anyone have any idea why this would be ?

Multiplus-II
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Alexandra avatar image Alexandra ♦ commented ·

@Scraggs

A little clarification is needed here.

Your post is titled Input watts incorrect, but you are talking about being offgrid. So where is the input watts going into? The battery or the AC input? Or are you referring to loads? or PV production?

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scraggs avatar image scraggs Alexandra ♦ commented ·
At the moment we are still connected to the grid and I have a 13 amp supply going in to the Multi just to keep the battery topped up, I also have a meter on the grid in.

The AC in to the multi is supplying nothing else just the charger.


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Alexandra avatar image Alexandra ♦ scraggs commented ·

Are you using the CT?


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scraggs avatar image scraggs Alexandra ♦ commented ·
Sorry to sound dumb but CT?
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Alexandra avatar image Alexandra ♦ scraggs commented ·

No not being dumb. It is me muddying the waters. Sorry. I read 48/5000 yours it is the 8000.

Some screen shots from VC or VRM would be handy here.

It is unusual to read grid lower than load if you have no solar contribution. And the batteries are not power assisting.

Do you have your grid set point or incoming current limit lower than loads?


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scraggs avatar image scraggs Alexandra ♦ commented ·
I will get some next time I charge the batteries again.

I turned it off overnight then oddly I noticed that the next day it was more accurate, so it is something I need to keep an eye on.
There is an incomming current limit set to 13 amps.


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1 Answer
Mike Dorsett avatar image
Mike Dorsett answered ·

Usual cause for discrepancy here is power factor. Are you checking your input Watts against Vin x Amps in? This will usually give an incorrect result as you are checking VA against 'real' Watts?

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