Smart Battery Temperature vs BMV Temperature Sensor

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bsqr asked Feb 23, '22

Smart Battery Temperature vs BMV Temperature Sensor

I have a system with Victron Smart lithium batteries, BMV-712 Smart with BMV temp sensor and VE.Bus for BMS. My low temperature charge disconnect signal comes directly from the battery internal temp reading to the VE.Bus BMS and then to various charging devices where the charging is disabled. My BMV temperature (from temp sensor connected to battery terminal) is always 6 to 8 degrees (F) higher than any of my smart battery temps (as viewed in the Victron Connect App individually for each battery).

I have two questions, is this kind of temperature variance normal? And is there any way to either calibrate the BMV temperature sensor to better match the internal battery temperature or to have my BMV-712 (and CCGX) actually use the same internal battery temperature that's fed to the VE.Bus BMS?

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Answer 1 · 2022-02-23T08:40:56Z

Stefanie (Victron Energy Staff) answered · Feb 23, 2022 at 08:40 AM

Hi @Bsqr,

the VE.Bus BMS will always use temperature reading from the Lithium Battery. There is no way to feed BMV temperature into the VE.Bus BMS.

Yes, you can 'calibrate' BMV temperature in your GX device. Go to the temperature sensor and right click, then setup.

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bsqr commented · Feb 23, 2022 at 08:54 AM

I was actually wanting the BMV to be fed the same battery temp that the VE.Bus BMS uses (actual internal battery temperature) and not the other way around. I kind of figured there wasn't any way for the smart battery data to be fed to the BMV.

I'll look into calibrating the temperature that the BMV actually uses.

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Stefanie (Victron Energy Staff) ♦♦ bsqr commented · Feb 23, 2022 at 09:03 AM

That's not possible either. The BMV temperature is measured at battery plus pole while the SmartLithiums temperature is measured inside and in between the battery cells. So it's fairly normal that there are differences between both values.

I'm using a similar setup and noticed that battery internal temperature is more or less the same like the BMV temperature sensor, but I have altered the calibration settings slightly (maybe 1 or 2 degrees up or down) on both, battery and BMV. When calibrating, make sure you have a reference. I've been using a IR temperature sensor for that.

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