Victron Battery Monitor: Strange Readings

TNOutback

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

ChanW

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.

jkjenn

You are still getting parasitic battery drain. You would have to turn the battery disconnect off to get an accurate reading.

Cbusguy

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.  

TNOutback

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.

jkjenn

Where is your Victron wired? Is the inverter wired to the shunt?

N7SHG_Ham

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.

TNOutback

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.

N7SHG_Ham

@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.

TNOutback

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.