I’ve been wondering this for a while now but are my BMV-712 values supposed to show negative while just charging? Here are a few pics to show you what I mean. Everything seems to work properly. I have it on shore power and the Multiplus 12/2000/80 (when in Run mode and not Charge mode as shown in pics) will pop on the instant shore power goes out, so that appears to be correct…I’m just curious about these numbers in the display panel:
Thanks!
The BMV normally shows positive when charging and negative when discharging. Have you got the shunt wired the correct way around with all negatives to the shunt system side and only the shunt connected to the battery. The other issue may be a slight out of calibration error, the manual has a zero current calibration method.
I assumed it was wired correctly because the volts shows a positive value, wouldn’t everything be negative if it was wired wrong?
Also, forgot to ask in original post, but the temperature isn’t showing either, and I went over the wiring for that also and think it’s correct. Is there a setting in the Multiplus unit for it that I might have missed? Google AI fwiw says it requires a “special” temp sensor but I’m using the one it came with. Thoughts?
The positive and negative connections will always be the right way for voltage. The shunt has 2 negative connections, the negative current has to flow the right way between these, so you can get the 2 negatives the wrong way.
If you have wired the Multiplus temperature sender to the Multiplus it should just work, I do not think there is a setting. However there is no way to display it.
You can add a temperature sensor to the BMV but that is a different type to the one used in the Multiplus.
Thanks for the info. I just flashed the firmware in the BMV and it exposed a new “76” setting option which reverses the shunt. Now everything looks correct in my numbers. I’d guess they added that for people like me, or perhaps for complex installations that got the wires wrong and it would cost too much to go back in and fix them.
I also removed the temperature output option from the BMV display since I apparently don’t have a BMV temp sensor, I just have the Multiplus temp sensor and the MP doesn’t have a bluetooth app to read the sensors remotely I’m guessing…
You can get a Bluetooth dongle to output the Multiplus operating info, I do not know if it displays the battery temperature. You would have to research this.
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