Victron Battery Monitor: Strange Readings

TNOutback
TNOutback Member Posts: 633
edited February 2020 in Battery/Electrical & Solar
Got my Victron BMV-712 installed in my 400, entered all the settings for the AGM batteries, and I’m seeing some weird readings on amps, wondering if I’ve missed something. With everything I can turn “off” in the camper off (refrigerator, Alde, inverter, lights, TV unplugged, etc.), the Victron is reading a 3 amp draw. That seems really high for parasitic loads for the inverter(?), propane detector, stereo/dvd player.  Oddly, if I turn on the inverter at this point, the monitor reads a 1 amp draw.

There is a zero load calibration in the app, but I don’t know if that would be helpful, especially since I cannot isolate the inverter.

Ideas?

Here are my settings for the Harris 6V AGMs:

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

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Comments

  • ChanW
    ChanW Member Posts: 3,165
    edited February 2020
    That could be right. I think there's a chart here somewhere that @jkjenn put together telling the common 'draws' of things in the 360. I'm thinking the detector and the stereo together could be pulling an amp. Edit: maybe a half amp... Jenn's chart is here: https://jenngrover.com/2015/11/guilty-as-charged-rv-battery-use-management/
    You should be able to pop the fuse for the inverter, to see what phantom draw it has.
    Chan  -  near Buffalo NY
    2014 S Maxx
    2011 Tacoma 4cyl ... edit: 2022 Tacoma 6cyl - oh yeah! 

     A_Little_T@b'll_Do_Ya
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  • jkjenn
    jkjenn Member Posts: 6,417
    You are still getting parasitic battery drain. You would have to turn the battery disconnect off to get an accurate reading.

    2021 T@b 320 Boondock "Mattie Ross" | 2021 T@b Nights: 239 | Total nights in a T@b 455 | 2022 Jeep Grand Cherokee L Overland | T@b owner since 2014

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  • Cbusguy
    Cbusguy Member Posts: 771
    there is a place in the 712 were you set the zero current draw calibration and charged capacity in the victron setup in the app.   Could be the zero current calibration is off????   Don't know,  just a place to start.  
    2009 GMC Canyon,   3.7 liter 
    2020 320s Boondock lite, With Lots of mods
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  • TNOutback
    TNOutback Member Posts: 633
    edited February 2020
    Thanks @jkjenn @Cbusguy.  My inverter is wired before the battery disconnect, so even with that turned off, I assume I would have a parasitic current from the inverter in the readings.  So, I’m not sure how I would get a zero current situation without disconnecting the inverter.
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  • jkjenn
    jkjenn Member Posts: 6,417
    Where is your Victron wired? Is the inverter wired to the shunt?

    2021 T@b 320 Boondock "Mattie Ross" | 2021 T@b Nights: 239 | Total nights in a T@b 455 | 2022 Jeep Grand Cherokee L Overland | T@b owner since 2014

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  • N7SHG_Ham
    N7SHG_Ham Member Posts: 1,261
    If the inverter is OFF, I don't think any circuits there are getting power? Not sure of your inverter or how it is installed, BUT that is my experience with several different inverters.

    I don't think the other small drains like detector, radio, etc. would be drawing anywhere near 3A in the idle state.
    2019 T@B 400 Boondock Lite
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  • TNOutback
    TNOutback Member Posts: 633
    Nucamp wired the inverter right after the distribution block, and before the battery disconnect.  So in order to get to a point to set a zero current calibration, I would need to disconnect both incoming (solar charger) and load (at distribution block) to isolate all currents.  A bit of a pain, but doable I suppose.
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  • N7SHG_Ham
    N7SHG_Ham Member Posts: 1,261
    @TNOutback, aren't you going to need to wire both the solar and inverter across the BM 712 shunt anyway if you are after every electron in and out of your battery? While you have wires disconnected for that you can see what the no load current is.
    2019 T@B 400 Boondock Lite
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  • TNOutback
    TNOutback Member Posts: 633
    edited February 2020
    I’m thinking the plan would be to wait for nighttime so I have no solar charging, then disconnect the negative battery terminal at the distribution block - then hit the zero load calibration button in the Victron app. That should ensure I have no charging or load flow.

    I’m now thinking there is very little or no parasitic load on the inverter when it’s “off”.  I noticed that with my battery disconnect in the “open” position, the amp production (current) indicated by the solar charge controller app also shows up on the BMV-712 monitor as “positive” amps. That is, when the disconnect is open, the solar controller and the battery monitor are showing the same amp value.
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