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dgorman avatar image

BMV Bug? - BMV vs Lynx Shunt in wild disagreement of SOC

Screen Shot 2020-09-20 at 5.11.12 AM.pngScreen Shot 2020-09-20 at 5.11.27 AM.pngScreen Shot 2020-09-20 at 5.14.16 AM.pngScreen Shot 2020-09-20 at 5.14.51 AM.pngHi,


I've been running the BMV for a few years and have ~60 automatic sync. I also have been running the lynx shunt for a while with about 10 automatic syncs. I've confirmed the settings between the two and interestingly they are wildly off between them. I've tried a couple of things and have some examples below. I've set up a rPI + grafana/influxDB to capture data at higher resolution than VRM portal so I can look at the data in different ways.


The large vertical jumps on the Battery SOC is from me forcing the SOC to match the Lynx to see how the slopes match up. The interesting things here is that the Ah Consumed match up pretty close with the Lynx SOC but not even close on the BMV.


With the the value right now, you can see I've consumed about 86Ah of battery power (86/1200), or about 7% based on the BMV stat. This is almost perfect with the Lynx showing 92% SOC, but the BMV shows 84% SOC. I then forced the BMV to be 92% a few min ago to see if this lines up.

While the Lynx CANBUS updates are slower than the BMV, there might be a bug with the BMV?


Grafana screenshots and BMV + Lynx settings attached. Am I missing something here?


Thank you!!



BMV Battery Monitorlynx shunt
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I realized on the Lynx current graph I was using the wrong value, it now lines up almost exactly. Still have the same problem though. The BMV is SOC is still way off and did a 50% discharge to see if I can get it to learn correctly?

3 Answers
Daniël Boekel (Victron Energy Staff) avatar image
Daniël Boekel (Victron Energy Staff) answered ·

Hi @Dgorman

are both monitors showing the same current?

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Hi,


BMV shows slightly more current. The Lynx shunt has another Lynx bus on the non-battery side whose negative terminates at the battery side of the BMV shunt. The ground side of the BMV shunt has all the negative loads (Quattry, MPPTs, etc etc)

Volts should be (A), didn't change the legend. ;)

Here is a fixed screenshot with the graphs using the same colors for BMV/Lynx for easier reading.

dgorman avatar image
dgorman answered ·

Here is another good example. Notice that the aH drawn is 125aH, which is 10% and Lynx is correct but BMV isn't.


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dgorman avatar image
dgorman answered ·

Curious if anyone had thoughts on this.

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