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lehrling avatar image
lehrling asked

BMV-712 Smart on VE Smart Network

I have just installed a BMV-712 Smart to my solar system and added it to the network with my SmartSolar MPPT and Smart Battery Sense.

I did not purchase the optional temperature sensor for the BMV as I (and my dealer) believed that the BMV-712 would get temperature from the network, it does not.

The BMV allows for monitoring only one of either start battery, battery temperature or midpoint battery voltage.

Now that I have already wired and set my BMV to monitor battery midpoint, I can no longer have battery temperature, even with the extra optional sensor.

What information does the BMV see and use from the network? Is there any benefit having it connected to the network at all?

Victron – can this be changed in firmware?


BMV Battery Monitor
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wkirby avatar image
wkirby answered ·

The BMV is supposed to provide information to the network. It would provide temperature information to the network if that was the chosen option.
The BMV would have no use for received temperature information over the network. Only the MPPT / chargers would have use for more accurate real time temperature measurements from the BMV if that is what the user has chosen to use that input for.

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lehrling avatar image lehrling commented ·

Can the BMV not calculate reduced battery capacity as battery temperature decreases?

What information does the BMV see and use from the network?

Is there any benefit having the BMV connected to the network with my installation?


Thank you.




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lehrling avatar image lehrling lehrling commented ·

The BMV can indeed adjust battery capacity to temperature.

This reinforces the point that the BMV should (because it is smart) be able to get temperature from the network, just like the MPPT controller can.

Victron – can this be changed in firmware?

From the manual:

The temperature measurement can also be used to adjust battery

capacity to temperature, see section 4.2.5, setting number 68.

The available battery capacity decreases with temperature.

Typically, the reduction, compared to the capacity at 20°C, is 18% at 0°C and 40% at -20°C.

68. Temperature coefficient

This is the percentage the battery capacity changes with temperature, when temperature

decreases to less than 20°C (above 20°C the influence of temperature on capacity is

relatively low and is not taken into account). The unit of this value is “%cap/°C” or percent

capacity per degree Celsius. The typical value (below 20°C) is 1%cap/°C for lead acid

batteries, and 0.5%cap/°C for Lithium Iron Phosphate batteries.

Default 0%cap/°C

Range 0 – 2%cap/°C

Step size 0.1%cap/°C



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siletzspey avatar image siletzspey lehrling commented ·

In a networked environment, the BMV is considered the best source of certain kinds of information, like temperature, voltage and tail current, since it (the shunt and temp probe) sit closer to the battery than any other devices. Think of the BMV as the intended distinguished authority and single source of truth when many devices are networked. As such, the BMV does NOT get values from the MPPT controllers, but rather the MPPT controllers start getting some values from the BMV.

If your MPPT devices rely on the BMV for some values, your system performance should be a little better. Read the section on tail-current monitoring in a system with more than one MPPT, and how it is better if the MPPTs rely on the BMV for a consolidated view of charging activity rather than taking their own local readings.

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lehrling avatar image
lehrling answered ·

To take advantage of BMV-712's ability to adjust battery capacity to temperature, I have decided to install the optional temperature sensor.

I do have a SmartBatterySense installed already but sadly the BMV-712 Smart is not smart enough to get battery temperature from the network.

My understanding is that my MPPT controller can also then get battery temperature from the BMV, awesome.

In the interest of keeping my installation clean, I thought I would remove the SmartBatterySense and rely on MPPT getting both battery voltage and temperature from the BMV via the network.

Does anyone know with certainty if the BMV with optional temperature sensor will send both battery voltage and battery temperature to the MPPT?



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lehrling avatar image
lehrling answered ·

@siletzspey, I am not doubting your statement that the BMV is considered the best source of information on the network.

I am asking however, if the MPPT will use the battery voltage information from the optional BMV ASS000100000 temperature sensor on the network.

It is all good to just say it should, already made that mistake when I thought the BMV should use battery temperature from the SmartBatterySense on the network. With Victron one needs to readjust one's understanding of the words "smart" and "network".

I have searched the manuals, there is no information on this. (unless I missed it)

I have searched posts and did find this statement:

"Yes the single ASS000100000 temperature sensor provides BOTH the voltage & temperature reading to the BMV"

OK, but will the MPPT use the voltage?

The sensor is not likely expensive, but if it cannot and will not give my MPPT both at-battery temperature and voltage sense, I will leave system as it is and not bother to order, pay shipping, and spend time installing.

Can anyone using this setup please confirm that the MPPT will use the BMV temperature sensor as remote voltage sense?

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