Victron Battery Sense - Temp Monitoring

[12vDC]

I am wanting to add a Smart Sense to compliment my Victron components.
The literature purports to further optimize charging by adjusting voltages with regard to temperature of the batteries.

I am currently monitoring voltage for both the starter battery and the house bank at the BMV shunt with the included leads. If/when using the optional accessory temperature sensor it displaces the voltage monitoring leads. I want to keep the existing dual bank voltage monitoring - and with a Battery Sense I am hoping to add the temp monitoring. The Battery Sense also adds another layer of cold temp charge protection, as I understand it will invoke a cutoff at the MPPT(s).

I mention the optional accessory above to point out it measures temperature with a thermistor. But regarding the Smart Sense the Victron literature uses language such as, “You can mount the dongle itself directly on the battery.” Does not say “must” mount. Furthermore, It does not say where specifically on the battery it can or should be mounted.

1. Does anyone know exactly how the temperature is measured by the Smart Sense module? Surely it can’t be reading case temp through the adhesive backing? Is it measuring ambient?
2. Why can’t the VE network use the data provided by the optional accessory temp thermistor (via the BMV Shunt) to perform the same optimization function as through the Smart Sense? Or is this already a function and I missed the plot?

 

[12vDC]

Pics for reference only.

 

[sunshine_eggo]

1. Does anyone know exactly how the temperature is measured by the Smart Sense module? Surely it can’t be reading case temp through the adhesive backing? Is it measuring ambient?

It is measuring the temp of the mounting surface.

1. Why can’t the VE network use the data provided by the optional accessory temp thermistor (via the BMV Shunt) to perform the same optimization function as through the Smart Sense? Or is this already a function and I missed the plot?

Victron connection methods:

VE.Direct = Proprietary Victron USB-like serial connection to GX device (MPPT and Shunts)
VE.CAN = CAN compliant connection to GX device for VE.CAN capable MPPT (up to 25 daisy chained to one GX) OR CAN compatible BMS.
BMS-CAN = CAN compliant connection to Cerbo for CAN compatible BMS.
VE.Bus =Proprietary Victron interface for connections between their VE.Bus inverters and/or GX device.
VE.Smart = bluetooth network - mostly useful for small systems with no GX device. Mostly for sharing voltage, current and temp data.

Victron shunts:
BMV-700: no temp monitoring
BMV-702: BMV-700 + temp monitoring
BMV-712: BMV-702 + Bluetooth.
Smartshunt: BMV-712 minus control relay and minus display. Poor bluetooth range.

ANY BMV can share current/voltage data via VE.Direct cable to a GX device.
BMV-702/712 can also share temp with GX device

BMV-712/Smartshunt can share voltage+current+temperature via VE.Smart bluetooth network.

 

[Brucey]

I'm at the stage where I need to get a shunt, seems like the 712 is the best way to go as the BT antenna is located in the display head so a much better range than the smart shunt?

 

[12vDC]

BMV-712/Smartshunt can share voltage+current+temperature via VE.Smart bluetooth network.

thanks for that.

It is measuring the temp of the mounting surface.

@sunshine_eggo would you prefer a temp measurement off the battery terminal or somewhere on the case?

 

[sunshine_eggo]

I'm at the stage where I need to get a shunt, seems like the 712 is the best way to go as the BT antenna is located in the display head so a much better range than the smart shunt?

Yes.

EDIT: The proximity of the BT radio to the EM field of the shunt due to normal operation also adversely impacts the BT radio range.

 

[Brucey]

thanks for that.


@sunshine_eggo would you prefer a temp measurement off the battery terminal or somewhere on the case?

I have an SBS, I just have it hanging off a Redodo 12V 100Ah mini LFP battery. Because I want to know the ambient temperature of the area the battery is in, and also frees me to move the sbs to another battery if needed and not worry about the sticky pad. I wouldn't put a temp sensor on a terminal because it's going to be warmer than the rest of the battery and ambient temp and give you an inaccurate reading.

 

[12vDC]

I'm at the stage where I need to get a shunt, seems like the 712 is the best way to go as the BT antenna is located in the display head so a much better range than the smart shunt?

i get max range from my BMV as its mounted in the dash tray.


my battery bank is mounted under chassis in a metal tray. im thinking the smart sense bt signal may be inhibited. unless the smart sense bt connection is funneled through the bmv?

 

[sunshine_eggo]

thanks for that.


@sunshine_eggo would you prefer a temp measurement off the battery terminal or somewhere on the case?

I have found it doesn't matter.

I have 7 temp sensors:

3X on my Batrium BMS (side)
1 Smart Battery Sense (side) (almost never used because I can't get SBS data in VRM)
1 BMV-702 (terminal)
1 temp sensor on EACH of my Quattros (terminals)

I have found that there's a 5°C variation across the 7, so I accept that anything within 5°C is accurate enough. With that assumption, it doesn't matter whether it's on the side or a terminal.

 

[sunshine_eggo]

im thinking the smart sense bt signal may be inhibited. unless the smart sense bt connection is funneled through the bmv?

VE.Smart devices talk to each other.

VictronConnect communicates with the individual device to which it's connected.

 

[12vDC]

VE.Smart devices talk to each other.

VictronConnect communicates with the individual device to which it's connected.

ahh yes, why it has to buffer when you make a device selection in the app.

 

[Brucey]

i get max range from my BMV as its mounted in the dash tray.

View attachment 182814
my battery bank is mounted under chassis in a metal tray. im thinking the smart sense bt signal may be inhibited. unless the smart sense bt connection is funneled through the bmv?

The sbs BT signal is very strong should be fine. Make sure when you order you get the "long range" version. But if you have the 712 you should be able to use the temp sensor on that in a ve.smart network with your Victron scc.

 

[sunshine_eggo]

Yes.

i get max range from my BMV as its mounted in the dash tray.

View attachment 182814
my battery bank is mounted under chassis in a metal tray. im thinking the smart sense bt signal may be inhibited. unless the smart sense bt connection is funneled through the bmv?

If that's a BMV-712, your best bet is to replace the (+) wire with the temp sensor.

 

[12vDC]

If that's a BMV-712, your best bet is to replace the (+) wire with the temp sensor.

I begrudgingly agree.

Fine. I guess I can do without seeing the starter voltage on the app.

1st World problems…

 

[sunshine_eggo]

I begrudgingly agree.

Fine. I guess I can do without seeing the starter voltage on the app.

1st World problems…

if that's the case, then the SBS may be better.

You can put BOTH in a VE.Smart network. The BMV will feed voltage/current and the SBS will feed temp.

 

[12vDC]

if that's the case, then the SBS may be better.

You can put BOTH in a VE.Smart network. The BMV will feed voltage/current and the SBS will feed temp.

Confused now.

I thought the thermistor accessory would provide Temp *and* V/I?

 

[sunshine_eggo]

Confused now.

I thought the thermistor accessory would provide Temp *and* V/I?

The BMV temp sensor technically only provides temp and voltage, but the shunt itself provides the current.

My answer was in the context of if you want to retain the starter battery voltage monitoring AND get battery temperature data.

Addition of the SBS allows you to retain starter battery monitoring and gain battery temperature data.

My main point is that if you have potentially conflicting data on the VE.Smart network, there is a component preference, so you would still get all three pieces of data.

 

[Rocketman]

I found a different way to “see” starter battery voltage. I added a smaller solar panel and a 100/20 mppt to the chassis battery. That way I know the chassis is always full (that’s the real reason I added it ) & in the app history I can see daily voltages.

Other reason - I had a device that “stole” some of the house power to keep the chassis battery up. It was 23 years old and designed for lead acid house bank - it was always on 24/7 on the lithium - because the voltage is a little bit higher. So I took it out & added a panel for the Chassis battery.

I have the BMV712 with temperature sensor - it works well. The temp is measured wherever you place the sensor on the positive line.

 

[12vDC]

I had purchased the thermistor but decided for my particular install I was going to need to chop up the wire and add length and move the fuse out a little for (future) ease of access. Too much soldering. That and not liking the idea of possibly altering the resistance of the wire, I became discouraged and abandoned the thermistor idea. Ordered the Smart Sense instead.

I found when adding the Smart Sense temp sensor, the existing wired voltage sensor leads can remain! So I have both starter and house voltage readout, and the VE network temp monitor. So if for whatever reason my heat pads crap out, I have a backup low temp cutoff.

However, I will need to see if there are any side effects of having both the wired voltage sensor at the bus AND the Smart Sense voltage reading on the middle of three parallel batteries.

I was wondering should I place the eyelets of the Smart Sense monitor leads to opposing batteries to measure an overall bank voltage. The manual however, states to install on an individual battery. In the end, because my bank is installed underchassis inaccessible, I chickened out. I dont want to drop the tray again if it didnt work. I put it on one battery and bolted the tray back up.

It works for now ??‍ So far so good.

 

[12vDC]

Edit from my post above:

I found at least one issue.

The Smart Sense will indeed report the registered temp to the MPPT via the VE network and disable charging.
However, the Orion DCDC apparently does not accept the network temp reading.

To use the onboard relay of the BMV as trigger to disable low temp charging for the DCDC - the AUX INPUT must be set to TEMP (alternate submenu for selections of temperature for relay activation).

In short, I cannot keep the app display of the Starter voltage (Aux Input = Starter Voltage) if I want to trigger low-temp cutoff from the relay (the Smart Sense and Orion do not play well together).