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Igor Vuckovic avatar image
Igor Vuckovic asked

Multiplus II - proper configuration

Hello all,

I am new here and last days / weeks I have read many articles here but unable to find proper solution for my needs.

I using my Multiplus mostly as inverter...but have a problem how to configure it to work as charger only when battery voltage drops below for example 50V. So when voltage is lover but 50V (on 49.99V) then transfer to grid and also charge batteries.

How to configure it? For charger I see only options for absorption / float voltage. I have played with conditional switch to AC but again - it not works as I expecting.

Regards,
Igor

Multiplus-II
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Gian avatar image
Gian answered ·

Dear

To testing the ESS mode there can be configured according to the percentage of the battery between the electric network.

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Igor Vuckovic avatar image
Igor Vuckovic answered ·

So it is not possible to make it working on battery voltage level?

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sharpener avatar image sharpener commented ·
Yes you can using Assistants or NodeRed, but why would you want to? What are your objectives here?


ESS works very well for most people but is based on State of Charge not voltage. This is usually better because battery voltage depends also on current drain and recent history of charging/discharging.
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JohnC avatar image
JohnC answered ·

Hi @Igor Vuckovic

It's possible to do this with Assistants, which is a more detailed section in the Multi settings. But we would need to know more about your 'grid'. Like do you export power?, want to use ESS (an Assistant too), or is the grid just for backup for a standalone system? The more you can tell us, the better chance of finding a suitable solution.

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Igor Vuckovic avatar image
Igor Vuckovic answered ·

I use my Multiplus off grid, not export any power. It is connected on my 200Ah battery. Battery is charging with SmartSolar MPPT... Also have BMS 702 ... And Inverter part working perfect... Battery is enough for 2 days and in sunny days no need for any additional charges.... But since winter comes I will need Charger to take action.... I have set it same absortion / float voltage as my MPPT and that part also working as should (in case it start charging on same point)...

So I just wondering how to switch my load from Inverted to AC input and start charging when battery voltage drops bellow 50V?

Hope system explanation / question is clear.


Thanks,
Igor

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xury avatar image
xury answered ·

Do you need control it manually? Or without your attention?

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Igor Vuckovic avatar image Igor Vuckovic commented ·

Without my attention

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xury avatar image
xury answered ·

Have you got any GX device?

There are many ways to do this, but what is best depends on many factors.

First of all set sustain voltage to 50V to prevent battery deep discharge.

If you have GX like a Cerbo you can use Venus OS large with NodeRed, and simply switch between

ESS modes like "Keep battery charged", Optimized, and external control based on battery voltage level. But is not a best solution because it doesn't take battery SoC value into account.

You can use charge schedule, based of your own energy consumption prediction.

Generally, we are not able to obtain optimal results when relying only on the voltage value.

Second, it is not economically profitable. Better set the "minimum Soc unless grid falls" higher value.

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Igor Vuckovic avatar image
Igor Vuckovic answered ·

I have ordered Cerbo GX but it still not arrived.. I thought it is possible using Multiplus only... will wait Cerbo then, thanks for all your help

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JohnC avatar image JohnC ♦ commented ·

@Igor Vuckovic

Despite all the other options, what you want is fairly straightforward, and Assistants doesn't need a Cerbo. But you'll need to get your head around how they work. https://www.victronenergy.com/live/assistants:start

An odd link there too. Look for mention of the Ignore AC function, not an Assistant itself, but a target. The Generator one gets a mention to do this, but a simple Programmable Relay Asst could do this too if you wanted to use just V as a switch.

I won't go deeper yet. You need to have a look first and maybe give the Fake Target thing a try to see what you think.

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