Hi all,
here my vrm screenshot, as you can see the mppt is charging 73W and i’m using 22W of dc (some lights, router etc). the battery is charging 50w, so why the DC power is not negative?
if I use the Orion TR the DC Power goes negative meaning charging.
so why not the mptt for coerence? or I don’t understand how it works?
thnaks
If you do not have a SmartShunt on your DC loads set as an energy meter then the DC loads is only an estimate based on other info. See the DIY FAQ.
I have a smart shunt bmv-712 isntalled as main battery monitor. does it means that I need to buy another shunt and set it as energy meter? could you please explain better?
thanks
You have a BMV-712 as a battery monitor measuring what goes in and out of the battery which is very accurate. You have current measurement built in to your other Victron devices but this is slightly less accurate. You have DC loads that are not measured and also system losses. The calculation works these out as the difference between all known values. Most people are not concerned that the DC loads is not 100% accurate and use it as a guide. Some people want more accuracy so you install a SmartShunt to measure your DC loads very accurately. This can be useful with managed lithium batteries so the charging can add the current required by the DC loads to the current the battery required for charging. In the diagram below A would be your DC loads, C would be the inverter, solar and Orion.
thx for the clarification but in the diagram I have already C as inverter, solar and orion. I do not understand why adding a second shunt as “A” will measure correctly the solar that is already connected to “C”. All my loads are connected to “C” as descripted in manual. I add also that Orion has been measured correctly: when I turn on the engine on the dc loads goes negative in about 200W (18A*13v = 230w - 25W current loads). so why not mppt?
Sorry I got side tracked, your are questioning the fundamental basis of Victron’s presentation of the data rather than there being an error in the DC tile which I was answering.
In general Victron’s presentation is referred to the source in question. The solar tile is based on the MPPT as the source i.e. positive is out of the MPPT, the DC tile is based on the battery as the source, positive is out of the battery, negative is into the device, the inverter input is based on the grid as the source and the output on the basis of the inverter as the source. This is the consistent way that the data is presented. Victron could have made everything battery centric but that would be an issue. If you had a separate tile for the Orion then it would show positive flow when charging because that would be based on the Orion as the source.
ok, I think I understand, so the dc loads will still show the loads not considering the solar wattage coming in? 73w in solora, 22 out from battery = 50W charging. seems legit if I understand.
Yes, the DC loads is anything that does not have its own measurement so it does not include the solar nor the inverter.
Sorry to reopen this thread but I need more clarification:
This is the scenario in my RV:
So where the 21w of DC loads are going?
The DC box is just a calc and any errors in any of the readings distorts the value, it is only approx. Measuring low currents will have larger % errors.
I try to me more precis: this is data for my IP22 15A taken from VictronConnect App:
output 15v, 14.3A, battery 14,23V
so the IP22 is producing about 215W.
the ac charger tile is reporting correctly.but what about the battery tile?
it report just 137W and dc loads is reporting 78W (137+78 = 215).
The real loads are 21W (if I disconnect the ip22 from the grid I get that value and it is correcly reported by the bvm: about 1.7A at 13v)
could be a voltage drop? seems that i’m loosing 57W
p.s. I wrote the driver to show the ac charger tile for the IP22 ve.direct hack, V is taken from IP22 output, I is taken from IP22 output and P is calculated as V*I
finally I got it, system works perfectly. the missing 50W were going to the starter battery throught a parallelator (cbe csb3). thanks so much for the help
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