I’ve noticed that while charging via solar, the BMV-702’s value for watts being used fluctuates with the power coming from the charge controller, even when the load is steady. What might I be doing wrong?
I’m using a Raspberry Pi to read the data from the battery monitor. When I say `watts being used` this is the “P” value, which they document as `Instantaneous power`. Overnight when not charging this value is stable at about -19w which is a bunch of AC devices like cell modem, wifi, Rpi, etc. I understand this as it’s negative because it’s drawing power. As soon as the sun comes out, this value goes above zero, as expected because it’s now generating watts, but if I take the value that the charge controllers says is charging and subtract P-value, I still get a much higher number than roughly 19w and the graphs track with the intensity of the solar charge.
Obviously I’m not understanding something here?
300ah AGM (3x 100ah) batteries
Renogy Rover 60a Charge Controller
Renogy 2000v Inverter
Victron BMV-702 Battery Monitor
Wired:
Shunt wired between batteries and bus bar, everything else connected to the bus bar(s)
[1] http://www.tiarora.no/Victron/VE.Direct-Protocol-3.24.pdf
