Multiplus 2 48v 3000 & Small single battery

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ajspicer asked Jun 17, '22

Multiplus 2 48v 3000 & Small single battery

Good Morning,

We have a trouble free Victron setup in our camper van and would like to use quality Victron equipment in our home for an ESS system.

We have 2.25kw array and a Sunnyboy SMA inverter which is approx 10 years old on a uk feed in tariff.

We would like to use the Multiplus 2 48/3000 but with just one Pylon 2000C or one Pylon 3000C.

I understand that ideally 2 of the above should be used, is there any way to change settings in the Multiplus 2 to accept just one battery and what effect would this have on its performance?

We currently use a solar iboost to divert excess generation to our hot water tank. Will this work using ESS and if so will the batteries charge first then hot water or vice versa?

This has a current sensing clamp to detect excess power.

We would add another battery at a later date when we can afford more.

Many thanks for your help.

Andrew

Multiplus-II ESS

2 |3000

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Answer 1 · 2022-06-17T09:05:48Z

wkirby answered · Jun 17, 2022 at 09:05 AM

The problem is that there is no setting to limit the discharge current from AC-OUT. The output power is dependent upon the load.
A single US2000C can supply a maximum power of ~1.25kW (25A on the DC side).
A single US3000C can supply a maximum power of ~1.85kW (37A on the DC side).

The MultiPlus could supply 2.4kW which would be a lot more than either of those battery modules is designed to supply continuously. It can supply more for a few seconds.
You'd have to limit the ammount of load that you put on the system to prevent the battery from being discharged at too high a current.
The battery would most likely shut down when these limits are exceeded and the system would shut down, but you don't want to rely on the safety limits.

Sure, these battery modules are at really silly prices now, almost double the pice of a year ago. So you would not want to get one module, thrash it and end reducing its lifespan or damaging it.
Much better to save up for two or more modules and then install the system correctly to avoid problems later on.

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ajspicer commented · Jun 17, 2022 at 10:16 AM

Many thanks for your reply, Probably keep saving the pennies then. Do you have any idea about the comparability with the solar iboost? Or can you get the Multiplus to divert power to the hot water tank after the batteries are charged or Vice versa?

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Answer 2 · 2022-06-17T12:16:49Z

sharpener answered · Jun 17, 2022 at 12:16 PM

Perhaps you can get round the lack of battery current limit by limiting the inverter power in ESS

and/or the charge current in DVCC

I do the first to keep the DNO happy and change the second if necessary to keep the fan from running, seems to work. As a backstop you could add a 6 amp mcb on the Multi's output and change it later when you add the second battery.

Your iboost should continue to work. I have a similar setup, the current transformer for the diverter needs to be the first thing on the incoming mains, so only as and when the Multi has charged the battery and is trying to export does it turn the immersion heater on. Finally when the hw tank is hot (orange trace top right) it switches to actual export (blue trace top left).

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seb71 commented · Jun 17, 2022 at 01:11 PM

Perhaps you can get round the lack of battery current limit by limiting the inverter power in ESS

This has the downside that the inverter power limit you set there also applies when power comes from the PV array, not from the battery.

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Answer 3 · 2022-06-17T13:37:07Z

sharpener answered · Jun 17, 2022 at 01:37 PM

I think not provided the PV array is on the AC Out 1 of the Multi.

@ajspicer has only 2.25 kW of solar, which is OK with the 1:1 rule, so this is where I would suggest connecting it as it will stay generating if the grid is lost.

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