question

I just compared the various Multiplus I and II datasheets and there a zero load efficiency difference. Zero load is the inverters own power consumption when idle. Then when in usage, the efficiency is about 95%

For example the 240 V AC and 48V DC versions

MultiPlus-II 48/3000/35-32 - Zero load power 11 W

MultiPlus 48/3000/35 - Zero load power 25 W

The 120V AC - 12V DC versions for

12/3000/120 are 15W MultiPlus-II and 20W MultiPlus

The extra 25-30W may be attributed to power efficiency loss, however that is a lot as the average efficiency is 93% for both Multiplus I and II.

You can test this on larger loads of 2000 W power an appliance and see how much extra you are consuming then we see. Ideally you should consume 2000W + 140W to inefficiency. Let me know how it goes

see the datasheet below

https://www.victronenergy.com/upload/documents/MultiPlus-II-to-MultiGrid-and-MultiPlus-comparison-EN.pdf

@Michaeltenerife

There is a point where the system is more efficient. The other caveat is at low wattage (under 4amps) they are not so accurate in readings. Higher battery voltage systems have better conversions efficiency and the size dc cabling has an effect (@SEmmaH has mentioned a few good points in more detail.)

Is the multiplus the only device on the system? Or do you also have mppts and gx? Don't forget they also draw a bit as well. Then you have power factor as well (some led lights say they are 7W but have a PF of 0.5 so actually draw 14W from an inverting system

If you have no BMV then the amount being drawn from the battery is a calculated amount not an actual VA reading. Anyone who is serious about power will really only pay attention to what is happening at the battery.

@Michaeltenerife

And to add to what Alexandra and Semmah have said so far:

There is a document from Victron that describes the efficiency of Victron inverter and inverter/chargers very well. From the diagrams one can see quite clearly why the efficiency is rather poor at the upper and lower end of the scale.

This is a normal physical process, independent of the brand, where temperature plays a significant role and is nothing to worry about.

Worth to read: https://www.victronenergy.com/upload/documents/Output-rating-operating-temperature-and-efficiency.pdf

Allow up to 15-20% loss for DC/AC conversion and about 30W or so for the Multi, GX etc.

So yes, for a 100W load you will see around 150W. All normal.

The "idle" load will be disproportionate at low power loads but loss will scale, that's electricity for you.

Thank you for all the answers.... although they are saying different things. Not so easy but Yes, it might be a mix of things.

Is the MPPT draining power from the battery or is it using the sun power?

I have a mppt, a BMV and a Cerbo installed.

Right now I have 21W load but 49W draining from battery. So probably inverter is 12W or so seeing the links you sent me and the other 16W are the Cerbo and BMv?

Thanks a lot for supporting

If there is no sun, the MPPT is draining power. Its less than 1 Watt.

The Cerbo drains about 4 to 5 Watt

In my case I have the Multi Plus 2 48/5000. This unit is very efficient. But in any case, at very low loads I do not recommend to take the readings as absolutely exact. An error of 10 to 20 Watts is easily possible. You should not forget, there are no multimeters installed in the inverters. That are good but quite simple detectors to measure the current. The Power is then calculated. If you would like to have a highly precise Power measurement from 5000W down to 1W with 4 digits resolution, the measurement equipment starts to get expensive ;-)

A further comment:

In normal Inverter mode at zero load, the Multi Plus 2 48V drains 1,5 Arms. Thats already something.

If AES Mode is activated it drains only 40mArms most of the time and only very shotrly all seconds once a peak to about 1,5 A. In this mode the standbytime goes up dramatically.

I have installed a MP-II 12v/24v/48v 3kVA 120v (NOT 240), Smart MPPT, 712 Shut. I have on 410Ah Redodo LiFePO4 battery.

Airstream 2022 Basecamp 16X trailer. Recently completed the installation.
I must travel with a CPAP, BiValve.
Testing in the driveway, getting ready for my first trip of 3 weeks dry camping in the Everglades.

Test run in the last 14 hours, results are confusing me.
I charge to 14.4 at 82A, then Float at 13.8, AES is not enabled.

With a full charge of 13.78v, 0.8A, 100%, 64F at 5:41 PM last night (Xmas Eve).
I then disconnected shore power, pulled all DC Fuses, and turned off all AC breakers. At that time, I had AC OUT, L1: -12W shown in VE.Bus Smart HQ2045N.
MP-II switch is pressed in the forward position, Charge/Invert mode.

There is one Airstream DC "Black Box" still connected and it is linked to exterior running lights, brakes, with a 30Amp in line fuse.

As of 5:46AM this morning (Xmas day), I only have 13.27v, with Current -1.19A, Power -16W, Consumed Ah -14.2, State Closed, State of Charge 97%.

For only a 12 hour period, I did not expect such a large loss.

Questions: Is that much loss to be expected? If not what is? This morning I will pull the 30A fuse to the Airstream Black Box, fully recharge the batteries and tonight run the same test.

Thanks, and may your Holidays be spent with family and friends.