question

barkinza avatar image
barkinza asked

Can I configure my Multiplus 24/3000/70 to ALWAYS run on inverter (even with mains / gen power on)?

Hi. I appreciate the various features surrounding "weak AC", "current limiting" etc but for my own reasons I would prefer to use (any) AC input to ONLY charge the batteries and use Inverter output exclusively and permanently. In other words force the system to work as an "inline" UPS rather than a "bypass" UPS..


I can cope with any negative effects of load vs battery condition manually and at my own risk.


Is this achievable and if so, how? It doesn't look obvious to me in the manual.


Thanks very much.

Multiplus-II
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kai avatar image kai ♦ commented ·

You might already have considered this, and it doesn't answer your question directly - if you can power your loads from DC (battery voltage) as opposed to 240VAC you can remove the need for a conventional online UPS. All you need in that scenario is a battery charger + battery...

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Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

I am sorry to say it is not possible. It is bi-directional inverter/charger in one.

The transformers inside the unit do both jobs simultaneously. They are not able to isolate the AC-input and the AC-output while both are simultaneously connected.

This picture may help you to see why:


multi.jpg (44.1 KiB)
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barkinza avatar image barkinza commented ·

Guy, thank you very much for the prompt answer. I guess my only option is leave the AC off the unit permanently and buy a separate charger connected directly to the batteries. A bit of a waste of the awesome list of features by consigning the unit to being a (granted, great) inverter only..


Do you foresee any problems with my approach (besides cost and complexity which are my problem)? Provided the charger can keep up with my very modest load, I can't see any real issues but your input is most welcome and appreciated.


Bryn

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boekel avatar image boekel ♦ barkinza commented ·

that will work perfectly, only downside is the extra transition losses.

For bigger systems using another multi might be cheaper than using a 'real' battery charger, but the battery chargers have a wider input range so might work better with a weak grid.

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crilando avatar image crilando commented ·

@Guy Stewart, is there another device available to charge and to invert at the same time? Chris

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