Disable charger in Multiplus in cloudy days

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Elimac asked Dec 4, '18

Disable charger in Multiplus in cloudy days

Hello,

I have a system with 2x MPPT, VenusGx, Multiplus 3000/24/70 and 540Ah 24V battery bank.

I wonder if I can disable the Multi charger. This would be useful in the following situation: cloudy days in which I don't have enough PV power to feed both the Inverter (AC loads) and charge the battery. In these conditions, rain, and so on, I avoid depleting the batteries, so I turn on the Multi to work from GRID.

In this scenario, the Multi will begin powering everything, charge battery and AC out. But I believe I could still use the PV power to finish charge the batteries, and use the GRID only to the AC loads. Later when PV power is over, I would enable the Multi charger again to make sure batteries get 100% SoC.

Is this possible? In the Multi input current limit(on Venus), I can only set 3A as minimum. I don't want to load new VE. configure settings on Multi just for these specific situations.

MultiPlus Quattro Inverter Charger

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Answer 1 · 2018-12-04T11:39:17Z

wkirby answered · Dec 04, 2018 at 11:39 AM

It is possible to do this if you are using ESS.
Then it is possible to adjust the maximum inverter power to 0W.

Then you can see on the main screen ESS Reason code #7 (Discharge Disabled by user).

All PV is going to battery and AC loads are coming from grid.

I hope this is what you are thinking about.

PS. You can see some solar power is missing, this because I have DC loads (Venus GX, Cisco switch and SIP telephone) which are always on and cannot be controlled.

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Answer 2 · 2018-12-04T12:10:36Z

Elimac answered · Dec 04, 2018 at 12:10 PM

Thanks,

Yes, this is what I want, but I am not using ESS.

I don't think I can use ESS, as I can't inject anything on GRID. My system is more like offgrid, just with grid support when needed.

Any way to make this work without the ESS assistant?

(or, any way to use ESS in a offgrid/ grid as AUX configuration?)

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Answer 3 · 2018-12-04T13:58:31Z

wkirby answered · Dec 04, 2018 at 01:58 PM

In ESS it is possible to disable Feed-i Excess.

BUT, due to constant fluctuations in grid voltage it is not possible for this to be completely 0W. It will usually be -10W to 10W. I understand that in some countries even 1W Feed-in is not allowed, if so, then sure ESS will be no good for you.

Without ESS, then there is "Charge Current Control" assistant. This allows you to change the charge current between 0A (charger disabled) and a user defined maximum (with a liner range in between) using a low voltage 0-5V on an AUX Input on the MultiPlus. You could use a potentiometer or just on-off switch, but not control from Venus.
Also, you can configure this same assistant so that if AC-IN is present, then set charge current to 0A (disable the charger), if AC-IN is NOT present, then of course it can't charge anyway!

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Answer 4 · 2018-12-04T14:42:22Z

Elimac answered · Dec 04, 2018 at 02:42 PM

Thanks WKirby!

That is a very good idea - I haven't thought about using that assistant. Unforntunately, I am already using the AUX input on Multiplus for auto switching from PV to GRID at night (with charger enabled) to make use of off-peak tariffs. If only I had another AUX input... but I think the 3000/24/70 only has one aux. I'm also using the Vsense and Temp input.

I'll leave the original question open, but this was a nice answer!

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Answer 5 · 2018-12-04T21:07:12Z

Elimac answered · Dec 04, 2018 at 09:07 PM

Any other option in my case? I thought it could be easy in Venus GX menus, somewhere or something that I have missed, a setting with different value...

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wkirby ♦♦ commented · Dec 04, 2018 at 09:34 PM

I have been thinking, I'll post if I come up with anything that is not too crazy.

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Anil Ghatikar wkirby ♦♦ commented · Dec 05, 2018 at 02:46 PM

Can you have a look at ignoring AC settings using generator assistant in Venus .https://www.victronenergy.com/live/drafts:acin_ignore_timer_using_ccgx_gen_start_stop_example

So the grid is used during night time only and during daytime only when SOC is low below certain lime say 50 % or when high loads are applied which you are sure cannot be met by PV - Many combinations based on Battery voltage, discharge current, Time of day, Loads etc. are possible thanks due to wonderful generator assistant in Venus ( not in multi)

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Anil Ghatikar Anil Ghatikar commented · Dec 05, 2018 at 02:47 PM

OR In your case, you can also use the virtual switch to disable charger instead of Ignore AC . allowing the grid to pass through all the time but using charger only during night or anytime when SOC/battery voltage is low

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Elimac Anil Ghatikar commented · Dec 05, 2018 at 11:47 PM

I am already using that exact assistant! I always charge batteries at night.

What I want now is to make the Multi work in passtrough during the day (cloudy days) and let the PV charge batteries. I don't want to ignore AC in this case, because I want AC loads to still get power from grid.

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