Multiplus temp sense with shunt

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blankfrank13 asked Feb 19, '19

Multiplus temp sense with shunt

I have a Multiplus 12/2000/80, and a BMV 712. As I understand it, the temperature sensor should be connected to the negative terminal of battery bank, as it gets hottest there and is a better representation of the battery bank temp overall and recommended in the multiplus manual. I also have heard that there should be NOTHING between the negative battery terminal and the battery side of the shunt.

So my first question is: where should the temp sensor (that comes with the multiplus) go?

Question 2: I purchased an additional temp sensor for the BMV 712 (part # HQ1813), but I'm now wondering if I need it? Should both the Multiplus and the BMV712 have individual temperature sensor's?

Question 3: My battery manufacturer came with a temperature coefficient (24mV/C*). I have no idea what that means, but when I set up the custom charging parameters can i input it to give the multiplus or BMV 712 more data to properly charge my batteries ( (2) 12V 116ah at 20 firefly oasis g31's). 14.4V absorb, 13.5V float.

Thank you kindly,

Nick

Multiplus-II BMV Battery Monitor Phoenix Inverter Temperature Sensor

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Answer 1 · 2019-02-19T02:11:43Z

Mark answered · Feb 19, 2019 at 02:11 AM

The Multiplus temp sensor must ONLY be connected to the NEGATIVE battery terminal.

It is OK to connect the Multiplus temperature sensor directly to the negative battery terminal as it is an independent connection & will not effect the accuracy of the shunt reading (or the current to/from the battery).

The BMV temp sensor must ONLY be connected to the POSITIVE battery terminal & it also doubles as the positive supply to the BMV.

Unless you have a Venus device & enable shared temperature sense (a feature of DVCC) then yes you will need BOTH, that is IF you want the charge voltage from the Multiplus AND from the MPPT to be temperature compensated. (PS. You have not stated if you also have a MPPT in your system or not, I have just assumed this...)

If you have a MPPT then you will need to create a Bluetooth network between the BMV & MPPT to share the temperature reading.

Yes you can enter the temperature correction coefficients when you setup the system - this will need to be done separately for the Multiplus & for the MPPT (assuming you have a MPPT). You will need to use VE Configure to do this on the MultiPlus (and a MK3 to USB adapter) & Bluetooth to do this on the MPPT (assuming you have a SmartSolar MPPT).

Just be careful with the coefficient you enter as it is for the whole battery bank - as it seems you have 2x 12v batteries wired in parallel you can use the coefficient for 1 battery as is, but if you had multiple batteries wired in series you would have to multiply it by the qty of batteries in series.

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