sprinter2072 avatar image
sprinter2072 asked

Temperature for house batteries and voltage for both house batteries and chassis battery

I've dug around on this board and quite find the answer. I have a BMV-712 that monitors the house batttery voltage and can also do temperature. However, if I do temperature, then I can't use the plug to monitor the chassis battery voltage.

It seems like the best solution is to use the BMV-712 for voltage on house battery and chassis battery. Now I'd be missing temperature. However, I could get a Battery Sense which transmits voltage and temperature to an MPPT controller (I have two). Since the temp is used by the MPPT controller only, this seems like a good solution. The Victron portal would show voltage from chassis and house batteries and the MPPT controllers would compensate based on temp received from the Battery sense.

Is this the only way to make it work?

MPPT ControllersBMV Battery MonitorvoltageTemperature Sensorstarter battery
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3 Answers
Paul B avatar image
Paul B answered ·

Yes thats the correct way as the MPPT units control the charging,

If the MPPT units are the smart versions IE bluetooth then there is a voltage and temp bluetooth unit that I would suggest that you purchase and then setup this up as its wireless

if they are not smart version then maybe by the small bluetooth dongles fpr the mppt units

this way only one voltage/temp unit is needed for all devices.

The unit will also connect to the BMV712

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Mark avatar image
Mark answered ·

If you have a Venus device and a Victron Multiplus/Inverter, there is a future update planned to allow the use the temp sensor of the Multiplus & transmit it to the MPPT via the Venus device - this is via the DVCC feature.

This update is currently in progress & I am also looking forward to the release myself, as I have a similar problem (I am using the 2nd BMV input for battery bank mid-point monitoring)

In the meantime, yes you could use a Smart Battery Sense networked with the MPPT, just don't enable DVCC.

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JohnC avatar image
JohnC answered ·

Hi Sprinter. It depends somewhat on your setup, but the Victron mppt's also have temp measurement inside the blue box, and compensate using that. My own setup is well ventilated and close by the batts, and I've found it quite adequate over the last couple years.

That said, like Mark, I welcome developments that may include my Multi's batt terminal sensor into Venus OS.

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joeoffgrid avatar image joeoffgrid commented ·

Can you check the guesstimated temperature somehow?

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Mark avatar image Mark ♦♦ joeoffgrid commented ·

No I don't believe that the temperature measured by the MPPT is reported/visable to the user.

Please also note that the MPPT internal temp sensor only takes a reading in the morning before startup - it does NOT continuously monitor the temperature throughout the day (probably because the heat generated by the MPPT itself would skew the reading).

Refer to extract below;

"In case there is no external source for battery temperature; charger uses its internal temperature for battery temperature compensation. The temperature reading is taken in the morning; when the charger has been idle for at least one hour, i.e. when the charger is not actively charging a battery or supplying a load."

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Related Resources

Victron BMV battery monitors product page

Victron temperature sensor disambiguation table - which product supports which sensor

Additional resources still need to be added for this topic

MPPT Product Page

MPPT Error codes

MPPT 150/60 up to 250/70 Manual