question

timmermc avatar image
timmermc asked

External temp sensor with Smartsolar and BMV monitor.

Hi all,

I know that a Victron MPPT solar controller has an inbuild temp sensor. This sensor is checking the temperature once a day, probably when there is no sun and no load to the batteries. And compensating according to this measurement.

But how is this compensation working when using the external temp sensor connected to the BMV-702 in a VE.smart network with the Smartsolar 100/20.

Is this configuration compensating continuously, or also once a day.

If this is the case, then there is no reason to install this extra external temp sensor if the MPPT smart solar charger is only placed 0.5 meter next to the battery. It can only be useful if MPPT smart solar and battery are placed in individual spaces. Or in the case of continuous measurement and compensation.

Thank you for an answer.

BMV Battery MonitorTemperature Sensor
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2 Answers
Mark avatar image
Mark answered ·

When temperature is transmitted to a MPPT via the VE Smart Network from a BMV-702/712 or Smart Battery Sense, the MPPT receives the temperature in real time and compensates the charge voltage as required throughout the day.

Also note that battery temperature can be significantly different to the near by air temperature. This is because;

A) A battery has a large thermal mass & takes a long time to change temperature as a result of the ambient air temperature around it changing.

B) A battery will generate heat itself during charging & discharging - particularly at high charge currents.

These are the other reason why its better to measure the temperature directly on the battery & transmit in real time, rather than rely on the MPPT internal temperature sensor.

Extract from Smart Battery Sense manual;


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timmermc avatar image
timmermc answered ·

"the MPPT receives the temperature in real time and compensates the charge voltage as required throughout the day"

Hi Mark, I can't imagine a better answer to my question. Thanks.

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