Why does batterylife use grid to charge the battery?

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hectonath asked Jan 12, '24

Why does batterylife use grid to charge the battery?

Hello,

I have a problem with ESS and BatteryLife.

First thi is my system :
- 3 PV strings with 3KWc each
- 3 BlueSolar 250/70 MPPT
- 48V 500Ah tubular battery
- the Cerbo GX
- 2 Multiplus II 5000/48 70 configured on parallel mode (only one 230v phase)

My problem is the Battery Life algorithm use grid to charge the battery.

It not use a lot, just about 100 W but I don't understand why.

There is some screenshots to illustrate that :

1) BatteryLife is on and Active SOC Limit is 80%.

Has you can see, the system use 52W (318 - 266 = 52) of grid to chage the battery

2) If I turn off BatteryLife

The system use the battery to feed the loads (grid set point is 50W so the 36W consummation
of grid is normal)

This comportement is OK because the minimum SOC parameter is set to 50% and the battery state is upper (74%)

3) Now if turn on Battery Life again

The system only use solar energy to charge the battery

I think it always should be the correct comportement

4) But if I wait a few minutes, without changing any parameter, the algorithm use again grid to charge the battery

Does anybody understand that and can explain me please...?

Thanks

ESS batterylife

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Alexandra ♦ commented · Jan 12 at 06:29 PM

@hectonath

What in have been seeing alot recently that has been causing issues is updates on parts of the Victron system, but not all. Usually the inverters are skipped. Or one other component. And this causes problems.

Are all your components of the same era of firmware. As in all left at their system commissioned firmware, or are they all on the latest?

If they are half and half. Update them all. And re program. And check

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hectonath Alexandra ♦ commented · Jan 12 at 08:02 PM

Thank you for your answer @Alexandra but I have checked the firmwares just before.

Has you can see, there are all up to date :

But I don't know if the 2 parallelised Multiplus II are individually up to date.
On this screen we just see one Multiplus II (with non serial number).

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Alexandra ♦ hectonath commented · Jan 12 at 08:22 PM

@hectonath

Noted. So not something overlooked.

So my next thought is that the system has raised the ve bus terminal voltage slightly when the change happens to make the system pass through while the solar charges the battery. Since power likes to flow from greater potential less.

This can make the watts value change there as w = v X a. So it is a calculation possibly not even what is being sent to the battery in amps.

With the system not having a BMV it sort of guestimates what is heading there since the ve bus doesn't actually measure amperage.

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hectonath Alexandra ♦ commented · Jan 12 at 08:31 PM

@Alexandra

Ok

so do you think that if I put a BMV to really control the battery energy flow, the problem will be resolved?

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Alexandra ♦ hectonath commented · Jan 13 at 04:09 AM

I think it would improve accuracy of readings, since the inverters only measure their terminal voltage.

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Modifications Space

Node Red Space

Answer 1 · 2024-01-13T03:45:37Z

Paul B answered · Jan 13 at 03:45 AM

Try the latest multiplus/quattros firmware first as there us a new selection tick box next to the assistants tab when using ve configure that may help with your question

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Answer 2 · 2024-01-17T07:39:21Z

hectonath answered · Jan 17 at 07:39 AM

Hi,
I have opened VE Configure to see more about the trick box and I have see that a new version of ESS assistant was ready.
So I update this assistant and the problem seems to be a little bit less but there still up to 50W goes from grid to battery, not always but some times.
I think it is probably a poor accuracy energy reading. I will see if I can put a BMV on the system in the future...
Moreover, I have read more about the trick box than Paul was speaking but as you can see, I thing it is not a good idea in this case beacause, this is a home system whith ESS.

Thank you @Alexandra and @Paul B to have helped me and I will tell you more when I will put the BMV...

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