Quattro Split Phase - Different low battery settings

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solardude asked Jun 5, '19

Quattro Split Phase - Different low battery settings

I am installing 2 of the Quattro 48/5000/120V inverters in split phase. Can I set the low voltage cut out differently on each inverter? Or does the software sync that setting? The reason I ask is that L1 has an air conditioner, and L2 does not. I was hoping to set the inverter LVCO on L1 so it shuts off soon after the MPPT's stop charging (at sunset). Then, I would set L2 at a much lower LVCO so the fridge and essential circuits continue being powered all night.

I have 2 banks each of 5000w PV, each with a 250/100 MPPT charging its own bank of 600Ah LiFePo4 batteries. I have plenty of battery, and plenty of PV, but I don't want the air conditioner to drain the battery all night and wake up to a thawing freezer.

Any thoughts or ideas are much appreciated.

split phase

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Daniël Boekel (Victron Energy Staff) answered · Jun 05, 2019 at 05:31 PM

Hi @solardude

You could use the second AC output of the Quattro's to switch off under low SOC conditions, but the Quattro itself would still be powered, thus drawing a small load.

Do you have any loads that need a split phase? otherwise you might just treat the Quattro's as two separate single phase units like Wkirby suggested.

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Answer 1 · 2019-06-05T16:42:05Z

wkirby answered · Jun 05, 2019 at 04:42 PM

This would probably result in error code 1 on the other one and it will switch off too. It would be very bad to drop one leg and keep the other one running,
If you want to separate your loads out then you'd need to run the Quattro's independently.

A better option would be to prevent the air conditioner from powering up at all under a low battery event then you can keep your split phase system as it is.

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Answer 2 · 2019-06-05T19:27:34Z

solardude answered · Jun 05, 2019 at 07:27 PM

@Daniël Boekel (Victron Energy Staff) I have a stove that uses 240V so I do need to set it up in split phase. FYI, this is off grid with generator, but trying to run 100% solar/battery if possible.

You mentioned being able to use AC2 output and switch it off under low SOC, how do I do that? I was under the impression that AC2 could only be used if the AC input was active, ie shore power or genset. If I could have it work without AC input, that would be amazing. Small power draw isn't a problem.

@WKirby, thanks for the input. I'll make sure that I don't drop 1 leg. I think if AC2 output option above doesn't work, I may have to wire in a relay for the air conditioner, and activate it based on SOC.

Thanks again for the help, this forum looks to be a great source for info.

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Daniël Boekel (Victron Energy Staff) ♦♦ commented · Jun 05, 2019 at 07:46 PM

You can use assistants, this will overrule default behavior.

based on voltage (not ideal for LiFePO4 or Lead-Acid batteries)

based on SOC:

more on using assistants:
https://www.victronenergy.com/live/assistants:start

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solardude commented · Jun 05, 2019 at 08:58 PM

That should work great, thank you.

I assume both inverters need to be programmed with identical SOC settings for ACOut2?

Also, since I’m not using an autotransformer, I assume it will be best to try balance all the loads on L1 and L2?

Thanks again.

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Daniël Boekel (Victron Energy Staff) ♦♦ solardude commented · Jun 05, 2019 at 09:47 PM

That's usually the most efficient.

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solardude Daniël Boekel (Victron Energy Staff) ♦♦ commented · Jun 06, 2019 at 01:59 PM

@Daniël Boekel (Victron Energy Staff), is it possible to always enable AC2 Out whenever AC1 in is active, but then disable it if battery is below "X" SOC, and AC1 In is not active? I understand I should use 2 instances of the relay assistant to enable/disable AC2 out based on SOC, just not sure if it will cause a conflict if I add a 3rd instance that enables AC2 Out when AC1 In is active. Hopefully this makes sense? Sorry for all the questions.

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Daniël Boekel (Victron Energy Staff) ♦♦ solardude commented · Jun 06, 2019 at 02:04 PM

Usually the easiest way to do that is to use the 'generator start/stop' assistant, this has multiple options in one assistant.

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solardude Daniël Boekel (Victron Energy Staff) ♦♦ commented · Jun 06, 2019 at 02:13 PM

Can you walk me through how to do that? I am using the fake target to simulate it, but can't see how to use the gen start/stop to accomplish it. Thanks for the assistance, this is my first Victron install. I have installed many other systems, but I'm still learning how to use the Victron products. I really love the options and adaptability, it's just been a bit of a learning curve for me.

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Daniël Boekel (Victron Energy Staff) ♦♦ solardude commented · Jun 07, 2019 at 07:19 AM

Like this:

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