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5KVA Multiplus inverter transfer to mains when Battery alarms at LV

How can a Multiplus 5kva inverter feeding a off grid house Essential load be configured to switch the load back to mains power when the battery alarms at its LV setting .. It appears I need a separate AC transfer sw controlled by the Inverter interface . Any advice would be appreciated or where I can find any info on this ? The manual does not say anything about this mode , (just the UPS (no break mode ). which I do not want !

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2 Answers
JohnC avatar image
JohnC answered ·

Hi @caprod

Have you looked at using the Assistants onboard your Multi to do this? You may need updated firmware to succeed, but I'd be surprised if you couldn't work something in with this.

I actually have a 40A Latronics ATS. That would work, but those things aren't cheap. Mine's redundant (but not for sale), but before I ever drag it from the spares bin I'd test the Assistant options first.

Using Assistants comes with a bit of a learning curve, but you could try..

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Hi John, thanks for the comments , No - but I just had a look at that link you sent & looks like a can of worms ?? where does one start & which assistant?? as you say A big learning curve !! the problem appears not to be a simple fix & I would be reluctant to do a firmware update unless I am convinced that would help or solve the problem ..... I have been caught out with doing firmware updates in a past work life , causing all sorts of unwanted issues on other devices ! Finding the info I need is proving to be very difficult , hence I like the idea of a simple Transfer sw ??

I shall keep researching thanks again .



Virtual Switch might be easier to follow. It won't run alongside Assistants, but it's an alternative. Well described in the link below, and an example shown there is probably what you're after. You'll probably need to pre-empt a V-failure with a setting(s), but that's better than being forced, imho.

The main point I'm making is that you already have the hardware, and a little learning will give a professional result.

Thanks JohnC, I think you have nailed it , I had a look at the Virtual switch ignore lesson PDF & thats the solution I think , treats the mains supply as a gen set & transfers load to that when the inverter shuts down with a selectable delay to prevent cycling , just need some software to install & configuration stuff & should do the trick , many thanks for your advice , I shall give it a go .


jacola avatar image
jacola answered ·

Hi Caprod, so you want to make sure the essential load gets connected to mains (which you have despite being off grid ?) in case of battery low voltage ?
I have a similar need/thought. As i have seen multiplus go to some fault state and cut all loads, leaving me without power (despite mains being available) .. i installed a chinese cheap amazon 63A automated transfer switch (they are around 40-60€ depending on #phases), kind of in 'reverse' order .. main supply is from multiplus and backup is from grid .. so if my victron install fails for whatever reason to provide power, i go directly to mains. The switchover with those cheap ATSses takes 100-200ms, so PCs might reset, but better that than being off grid. These switches guarantee break before make and they are motorized, so they dont draw significant power, basically a motor mechanically switching interruptors/fuse breakers.


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Hi Johannes, yes thats basically what I want to do ! the existing modes are no break or UPS mode , I want the load to transfer back to mains if the inverter fails due to a low battery warning or some other fault ..In Australia a firm manufactures a suitable AC transfer sw 25A & 40A versions are available with a transfer time of less than 20ms which I think should not disturb a PC connected to the load .

I see that Victron also make a similar product :-

Looks like a 20A & 40 A transfer sw with good transfer times of 5-20ms so that might be an option as well , so obviously you configure the transfer sw on the inverter output , so than on a inverter output failure the transfer sw operates & returns the load to the mains supply . Should be simple to set up by the sounds of it !

The Chinese product will probably be cheaper , but sounds like its transfer times are rather long , may not comply to our Australian electrical regulations either

Thanks for your reply