Victron BMV-712 Readings???

Jbreunig

Just installed a Victron Energy BMV-712 Battery Monitor in my 2020 T@b 400 Boondock lite with built in solar panels on the roof. Do not understand the readings I am getting on the iPhone App. T@b indicator panel shows full charged battery, My volt meter directly on the battery shows 14.0 volts but the app indications are all over the place. The below indications are only a few minutes apart with no change in load. Not connected to shore power or the tow vehicle. Is there a set up/calibration step required? Also will the display in the battery monitor gauge drain my battery with the battery disconnect switch off? The display does not go out when I cut off the battery. Is there a way to turn it off? Suggestions more than welcome.

N7SHG_Ham

Did you set the bm712 for your particulars, battery size, etc. Something obviously wrong with those large loads showing!

pthomas745

Hit that settings wheel up there in the right hand corner. That is where your settings for your particular battery will be. 

Cbusguy

I would start with the gear as pthomas suggested,  there is a zero cal for current,  make sure you do that.....

I am guessing this maybe deeper than that,  I have installed a couple and have never ran into readings like that.

Sharon_is_SAM

Hopefully your numbers will align once you enter your battery parameters.  What batteries are installed?  

Regarding the display using excess power, the monitor is wired before the battery cut off switch and the display is continuous.  It has an extremely low draw.  We store our trailer for 6 months over the winter and our AGM does not drop below 99% SOC.  Just make sure to thoroughly charge your batteries before storing and turn the battery switch to off.  BTW, the installed TaB battery monitor (?KiB) is inaccurate - reads high.  Don’t rely on it.  Rely on your Victron once it is up and running.

TNOutback

if you if you have the stock Harris AGMs in the 400 (that’s what is in my 2020 400 BDL), then these are the settings to program:

Battery capacity:  224 Ah
Charged voltage:  13.2
Tail current:  2.0%
Charged Detection Time:  3m
Peukert Exponent: 1.12
Charged Efficiency Factor:  97%
Current Threshold:  0.1A
Time-To-Go Averaging Period: 3m

You may need to do the zero load calibration in the app, but you’ll need to do it at night when you have no solar, and disconnect the negative from the distribution block before calibration. 

Jbreunig

Will try the zero load calibration at night in the app.  I would think I could do it during the day and just put a blanket over the solar panels.  I have put in all the other settings with still no luck.

Tundra57

Make sure the voltage connections are correct. It doesn't matter what battery settings you set, it is impossible for the battery voltage to change like that. Either the voltage signal used by the Vicron for battery voltage is not connected or the battery wires are picking up noise for either an AC source or maybe the switching noise from the inverter. Does this unit have seperate power supply and voltage measurement wires? If not is there a setting inside to use the power input to measure? If the measure is seperate make sure it's connected correctly. Is there any way you could have the current shunt and voltage measurement wires swapped?

Denny16

First, the Victron battery monitor uses a large 3/8ths in/out connection ground shunt, battery connects to one side, load ground leads to the other, only way to get this wrong is to have the battery/load terminals switched.  The only positive connection is for temp and power to the shut circuit board, so if this was wrong, it would not work.
See: https://www.google.com/search?safe=strict&ei=neCAXsWoKfHB7gLTk4iwCw&q=victron+bmv-712+installation&oq=victron+bmv-712+battery+monitor+with+bluetooth+built+in&gs_lcp=ChNtb2JpbGUtZ3dzLXdpei1zZXJwEAEYADIECAAQRzIECAAQRzIECAAQRzIECAAQRzIECAAQR1AAWABg4B9oAHABeACAAQCIAQCSAQCYAQA&sclient=mobile-gws-wiz-serp#kpvalbx=_o-CAXvgx49f0A4fKisAP57

rh5555

@Jbreunig, do the numbers on the BMV-712 display jump around in the same way they do on the app?  If they do, I'd be suspicious of the cable between the shunt and the display, if they don't I'd be suspicious of the bluetooth link.

In answer to your earlier question, the BMV-712 drain on the battery is tiny; way less than the self-discharge of batteries - so no worries there.

Denny16

I just finished installing a CMV-712 and was getting various readings, until we sent the blue tooth application setup for our battery, then the readings started to agree between the application and display, and were what they should be reading.  Didn’t need to do a zero load calibration.  Once yiu have the nominal voltage reading in your fully charged battery, you can add that to the setup program to get accurate readings on charge level vs loads. 
cheers

Tundra57

Why would the readings be erratic because the battery type was set wrong? Seems wierd.

Denny16

Don’t know, but they were off until the setup was run.  Maybe it depends on the battery setup you have.  We have the factory Solar setup with the Victron MPPT controller, so maybe the setup was needed to get et them in sync?

cheers

jkjenn

I am curious as to why the zero calibration needs to be done at night? If you disconnect the solar from the load side of the shunt, the battery is not getting a solar charge.