question

Hi @Alexandra! First of all, many thanks for your long and detailed response. I will try and answer in an equally detailed manner:

> At the end of the day it is the battery you should be most concerned with.

I'm aware of that. But in my case, the battery is connected only to the charge controller (an EPEver/EPSolar Tracer 30A which is working perfectly, including providing me with very precise current measurements -- among a ton of other data -- via its built-in RS485 port) and to the inverter.

So, as nothing else is neither supplying charge nor taking it from the batteries, my expectation was to use the Victron reported VA value (which, divided by the voltage, would give me the current), along with the charge controller's current measurements, to monitor the battery.

This approach has the advantage of not only cost, but also simplicity and robustness (less equipment to install, less things to maintain, and less stuff to break). And given my experience in other contexts, it would work if only the Victron gave me usable (as in, minimally accurate) current (or VA) values.

> Since you have purchased from the less expensive units of the range you will be experiencing what happens when you do so.

It seems a stretch to call the Victron Phoenix "less expensive". In fact, its price is over twice the price of the equivalent EPEverEPSolar IP-2000-12-Plus inverter which has very similar specs to the Victron Phoenix (actually, it offers a larger/longer peak capacity at 4000W for 5 secs) *and* has a RJ45 MODBUS port (which I haven't tested yet, but from which I would expect to obtain at least the same data, and with the same accuracy, I now obtain from their charge controller). The Victron Phoenix advantages (from comparing their spec sheets) are (a) its ECO mode, and (b) its Dynamic Cutoff, neither of which are offered by the other brand. (But then, I'm having issues with the Dynamic Cutoff feature too, please see my other post here if you haven't already).

So you would ask, why didn't I buy the EPEver/EPSolar? The reason is that I really, really like my local Victron reseller. They are very knowledgeable and helpful, and they sold me my EPSolar controller some months ago, among a lot of other stuff. But they don't sell the EPEver/EPSolar line of inverters -- they only sell Victron inverters. And then I thought, "OK, it's twice the price, but certainly Victron is a better brand and their inverter will be at least as good or better than the EPEver/EPSolar". At least in terms of accuracy, your answer seems to be proving me wrong.

> So my advice get a bmv

I think that even adding BMV (which alone costs over half the price of a complete EPEver/EPSolar IP-2000-12 inverter), I would not have direct info on the inverter, specially its temperature, which I think is really important to monitor (please see my other post here). Please correct me if I'm wrong.

[To be continued]

[continued from my previous comment]

> and definitely move your plans up for a bigger bank. 100AH is not enough to feed the beast on full load.

I'm well aware of that, it's why I stated on my original post that my inverter was "being fed by a single (so far, during the tests)" battery; my planned final setup is with 3 of those LiFEPO4 batteries in parallel, for a total of 300Ah.

> I have a 1600va multiplus compact. Ran a short test with a 100W bulb I have no complaints with how the system measures.

Very interesting! Thank you very much for taking the time and effort to do all those tests and photos, much appreciated!

From the pictures, I see you have the BMV (the little round thing on top, right?) *and* a color monitor which I guess is a different accessory. Please excuse my ignorance, but:

0) Are these values being obtained from the BMV or from your Multiplus Compact?

1) Which BMV model you have, exactly? My local reseller lists 3 different ones: BMV-700, BMV-702 and BMV-712, it would be helpful to know which one exactly you are using.

2) I see the values you mention (16W "empty" -- ie, only your accessories -- and 118W with the 100W lightbulb -- which would mean an additional 118-16= 102W just for the lightbulb, which is indeed very precise) are all being reported not on the BMV display, but in the aforementioned color monitor. Is the color monitor simply reporting what the BMV is measuring? In other words, can I dispense with the color monitor and obtain these values straight from the BMV, preferably via Bluetooth? (I want to capture it on my Raspberry Pi computer and store all the data and then display it with Prometheus/Graphana etc, plus activate alarms etc)

3) If the color monitor (or some other accessory) is required to be able to display/capture the data, what kind/model exactly would I have to buy in addition to the BMV?

Thanks again,

-- Durval.

I saw. Congratulations.

I am running on the gx 2.72 (currently in beta testing so use the one lower than that).

481 on the compact.

1.56 on the 100/50 mppt