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mfred68 avatar image
mfred68 asked

adding a second multiplus ii as a generator backup

I rarely would need to go over 5000w with one multiplus ii, but when i do need more power, could a second multiplus ii be wired into the generator input to add more wattage when needed, but not consume idle power when not needed, this should reduce ide power to only one inverter but allow for twice the power when needed. is this possible?

Multiplus-IIGeneratormultiple inverters
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Alexandra avatar image Alexandra ♦ commented ·

@mfred68

I do want to clarify what you are asking here.

You want to power assist the generator output to provide more input power to an inverter that is running a load?

Are you planning on having a second battery bank?

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mfred68 avatar image mfred68 Alexandra ♦ commented ·
The idea is to have two inverters connected to the same battery bank, but only use one inverter as the master 5kw inverter, this is because inverters use quite a lot of watts in idle mode with little to no load, so the second inverter can be left switched off, (not drawing idle power), but be activated if the power demand exceeds 5kw by the master inverter, is this possible? or is the generator input only designed to charge the batteries and not add power to the inverter output?

(I don't yet have a system, I am still planning and designing my off grid system, so gathering as much information as i can before buying the components)

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Phil Gavin avatar image Phil Gavin mfred68 commented ·

This clip may steer you right.

https://www.youtube.com/watch?v=SsTkgoN6ENM

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Alexandra avatar image Alexandra ♦ mfred68 commented ·
No they are either one system or two different ones.


Unless you want to reprogram and wire every time you want to make it a 10kva or a 5kva.

Do you have one big load? It may be easier to separate the db loads.


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2 Answers
anieuwstadt avatar image
anieuwstadt answered ·

Can be done, but when there is more than one source of energy to charge the battery, the battery monitor internal to the "main" inverter/charger will not correctly track the battery's condition. If the battery does not have a BMS, add a SmartShunt and Cerbo GX to the system.

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Michelle Konzack avatar image
Michelle Konzack answered ·

Yes, if you connect the backup MP to the ACin from the regular MP, the backup would be seen like a genset but make sure, that the output voltage of the backup is 2-5V higher then the standard one

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