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peac avatar image
peac asked

MultiPlus II: dynamic load cut-off voltage

Hello,

is there a setting for a "dynamic load cut-off" in the MultiPlus II? I'm using a 24V system (with lead acid batteries) and i've set the cut-off voltage of the inverter to 22.4V (via the MK3 interface). This is working good, but i'm looking for a setting, wich "calculate" the cut-off voltage under a load condition.

For example, if i there is a 2kW load, the battery voltage will drop down to 21V (but that is ok, because there is a load). The inverter should not cut-off this load. But with my current settings, the inverter cut-off the load under 22.4V...

Could you please give me a hint? Or is this not possible with the MultiPlus II?


Thanks!

Klaus

Multiplus-II
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3 Answers
Paul B avatar image
Paul B answered ·

have a look in the assistants area under programmable relay option in there you can see many settings one can control the AC2 out relay on the mutiplus thus you could control any loads attached to that put. you can also set multi conditions ie voltage and load and both have to be met etc etc

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seb71 avatar image
seb71 answered ·

This is possible for sure when using ESS (check 6.3). You can manually adjust those 4 voltages.


I do not know if it is possible without using ESS.

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seb71 avatar image seb71 commented ·

Victron broke the old link.

This is the new link.

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peac avatar image
peac answered ·

Thanks for answering!

But I think, what I was searching for is the SOC. I've enabled the battery monitoring and let the inverter cut-off under 50% SOC (and restart at >55%). In the first days, this worked well but after 2 weeks, SOC is "incorrect calculated", i think...


I'm charging four 220Ah lead-acid 12V batteries (2p2s -> 24V system) with the Victron MPPT 100/30 solar charger. In the Multiplus setting, i configured the battery capacity to 440Ah. I've used the "flooded battery" preset for my batteries, set the efficiency to 0.8 and the bulk-capacity to 85% (default).


But the SOC stuck around 50% the last days, despite the batteries were (nearly) full charged by the MPPT solar charger. The voltages of the (new) batteries are approx. 12.8 V. So what is happening here? Is it, because I'm (almost) not using the internal charger of the Multiplus, but the MPPT solar charger?

Thanks!
Klaus

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seb71 avatar image seb71 commented ·

Inverter calculated SOC is not accurate at all.


You need to get a SmartShunt (or a BMV which also has a shunt), for a more accurate SOC, but even then it won't be perfect.


Battery voltage is a much better way to cut off the inverter to protect the battery from over-discharge.

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peac avatar image peac seb71 commented ·

Hello, thank you for answering! Ok, i would like cut-off depending on the battery voltage. But this is not working, when I use loads like 2kW (the battery voltage drops down below the cut-off voltage and the inverter turns off..). A dynamic cut-off voltage must be possible on this device, right?

This should work without a relay or a ESS...? Otherwiese the Multiplus would be a really useless device?

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seb71 avatar image seb71 peac commented ·

If you do not want to use ESS, have a look at the other assistants, as Paul B said. Maybe this can also can be programmed using other assistants. With ESS it is very easy to configure a dynamic cut-off voltage and that is what I use. I haven't tried other assistants.

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