Victron Battery Temperature Sensors: is there one sensor to rule them all?

[borednerds]

So I've been debating the BMV712 vs smartshunt for my system and the temperature sensing lead me down a rabbit hole for which I have not found a satisfying answer. Which temp sensor(s?) do I need?

I am planning to have my battery bank stored about 10ft from the rest of my system in an isolated, insulated and heated compartment. In the future, I plan to use either a cerbo gx or RPi4 running VenusOS.
My understanding is the following:
1) There is a battery temp sensor for the smartshunt/BMV712;
2) There is a battery temp sensor for the Multiplus;
3) there is a battery temp sensor for the Smart Solar CC; AND
4) there is the Smart Battery Sense, for remotely installed batteries.
5) (there is also a temp sensor in the JBD BMS, which may be accessible to the system, but more discovery is required here).

Then, in the victron documentation, it says that using multiple battery temp sensors will send conflicting information to the various components, but also that the components wont share the temp information?
From page 2 of the Smart Battery Sense manual

When can I use Smart Battery Sense ...and when should I avoid using it?

• Check the VE.Smart Networking compatible products list for compatible Solar Chargers.
• Smart Battery Sense is not needed, or allowed, in systems which are already controlled by a Color Control GX or Venus GX, see FAQ Q6 for more info.
• Smart Battery Sense is not needed for installations which already have a BMV-712 (battery monitor) with a temperature sensor accessory.
• For installations using a BMV-702 together with its optional temperature sensor accessory - for wireless connectivity consider adding a VE.Direct Bluetooth Smart dongle instead of a Smart Battery Sense.

If I am understanding this correctly, I should not use the Smart Battery Sense and simply run the temp sensor with the leads from the battery to the BMV712/smartshunt.

Will the BMV share the battery temperature information with Multi and the SCC to ensure proper temperature compensation during charging? Or do I need to run 3 temp sensors to the battery?

What if the plan is to add the cerbo/rpi4 later? Will the BMV temp sensor only share the temp data through the cerbo? Or will it share it over the smart network? I guess if this is the case, I should move up the timeline to get the cerbo/rpi online.

Thanks!

 

[borednerds]

Also, I was told by my victron distributor that the extra power cable that comes with the bmv712 can be used as a temperature sensor. This seems wrong to me because I believe the the victron bmv temp sensor includes a thermistor ...for measuring temperature?

 

[Rocketman]

My understanding based on my setup.

I have the temp sensor on the Smartshunt- I did not put the temp sensor from the Multiplus on (too difficult for my RV).

Through the “VE smart network” the Smartshunt will pass current, voltage, and temperature data to the mppt’s. I don’t know if it passed that info to the Multiplus (it seemed the Multiplus was a transmitter of data - not a receiver).

Later I began having difficulty with the voltage sense getting too far out (my setup issue - I have at least 10’ from mppt’s to batteries). So I finally setup the DVCC on my CCGX (GX device older than Cerbo). The DVCC works much better.

My recommendation (if it works for you), use the Multiplus temp sensor (it’s included) and get the Cerbo as soon as possible.

Also, you will need some way to “control” the Multiplus- on/off/charge only/invert only & set the incoming current limit. Just use the Cerbo for that. (Although the VE BUS Smart dongle is nice giving the info on my phone with all the other devices).

Use the BMV712 if you need the VE direct port (to connect to the Cerbo) much closer or you want a round display that is way inferior to the Cerbo or you want the relay that is in the BMV712 to control something else.

Good Luck

 

[sunshine_eggo]

Conclusive guide:

Temperature Sensors [Victron Energy]

www.victronenergy.com

Cerbo can use Ruuvi sensors as well:

Venus OS v2.80 - Ruuvi wireless sensors, Load monitoring, and more - Victron Energy

UPDATE 2022-02-16: Venus OS v2.81 till v2.84 has been released. Details in the change log on https://professional.victronenergy.com; those versions mostly contain fixes relating to v2.80 – no new features. It is recommended to update to v2.84. CORRECTION 2022-02-16: The Bluetooth Radio in the...

www.victronenergy.com

I put both Quattro sensors, the BMV-702, a SBS and 3 temp sensors from my Batrium all over my battery. They are tracked as a total of three separate temperatures, and I make a decision based on worst case.

So I've been debating the BMV712 vs smartshunt for my system and the temperature sensing lead me down a rabbit hole for which I have not found a satisfying answer. Which temp sensor(s?) do I need?

Both use the same sensor. See the link above.

I am planning to have my battery bank stored about 10ft from the rest of my system in an isolated, insulated and heated compartment. In the future, I plan to use either a cerbo gx or RPi4 running VenusOS.
My understanding is the following:
1) There is a battery temp sensor for the smartshunt/BMV712;

Yes

2) There is a battery temp sensor for the Multiplus;

Yes.

3) there is a battery temp sensor for the Smart Solar CC; AND
4) there is the Smart Battery Sense, for remotely installed batteries.

No. The SBS is only compatible with MPPT if in a VE.Smart bluetooth network. SBS has NO other means of communication than bluetooth. SBS can only communicate temp and voltage via VE.Smart. A BMV-712 can communicate voltage, temp and current to a MPPT in a VE.Smart network.

5) (there is also a temp sensor in the JBD BMS, which may be accessible to the system, but more discovery is required here).

Only if you go through the effort of integrating the BMS to communicate with a GX device - definitely non-trivial.

Then, in the victron documentation, it says that using multiple battery temp sensors will send conflicting information to the various components, but also that the components wont share the temp information?
From page 2 of the Smart Battery Sense manual

sharing is either by DVCC + SVS/SCS/STS in a GX device or VE.Smart.

If I am understanding this correctly, I should not use the Smart Battery Sense and simply run the temp sensor with the leads from the battery to the BMV712/smartshunt.

Correct and not even possible.

Will the BMV share the battery temperature information with Multi

Not without a GX.

and the SCC to ensure proper temperature compensation during charging?

Only if in a VE.Smart network.

Or do I need to run 3 temp sensors to the battery?

Two would suffice. BMV-712 or smartshunt and the MP temp sensor.

What if the plan is to add the cerbo/rpi4 later? Will the BMV temp sensor only share the temp data through the cerbo?

The GX takes over. Enable DVCC and SVS, SCS, STS and a single BMV-712 with temp sensor will share battery voltage, current and temperature to everything in the system that needs that information. No bluetooth communication is used. Data is shared over the devices' connection to the GX.

Or will it share it over the smart network? I guess if this is the case, I should move up the timeline to get the cerbo/rpi online.

IMHO, no Victron system with inverter, MPPT and shunt components should be without a GX device.

 

[Itsmedp]

Conclusive guide:

Temperature Sensors [Victron Energy]

www.victronenergy.com

Cerbo can use Ruuvi sensors as well:

Venus OS v2.80 - Ruuvi wireless sensors, Load monitoring, and more - Victron Energy

UPDATE 2022-02-16: Venus OS v2.81 till v2.84 has been released. Details in the change log on https://professional.victronenergy.com; those versions mostly contain fixes relating to v2.80 – no new features. It is recommended to update to v2.84. CORRECTION 2022-02-16: The Bluetooth Radio in the...

www.victronenergy.com

I put both Quattro sensors, the BMV-702, a SBS and 3 temp sensors from my Batrium all over my battery. They are tracked as a total of three separate temperatures, and I make a decision based on worst case.

View attachment 156819




Both use the same sensor. See the link above.



Yes



Yes.



No. The SBS is only compatible with MPPT if in a VE.Smart bluetooth network. SBS has NO other means of communication than bluetooth. SBS can only communicate temp and voltage via VE.Smart. A BMV-712 can communicate voltage, temp and current to a MPPT in a VE.Smart network.



Only if you go through the effort of integrating the BMS to communicate with a GX device - definitely non-trivial.



sharing is either by DVCC + SVS/SCS/STS in a GX device or VE.Smart.



Correct and not even possible.



Not without a GX.



Only if in a VE.Smart network.



Two would suffice. BMV-712 or smartshunt and the MP temp sensor.



The GX takes over. Enable DVCC and SVS, SCS, STS and a single BMV-712 with temp sensor will share battery voltage, current and temperature to everything in the system that needs that information. No bluetooth communication is used. Data is shared over the devices' connection to the GX.



IMHO, no Victron system with inverter, MPPT and shunt components should be without a GX device.

Question for you…I went down the rabbit hole too and now I have to (2) SBS, multi, and BMV sensors I’m trying to figure out how to setup. Based on your comment it sounds like you are sharing temps for all your sensors over DVCC but SBS only shares over VE network. Can I assume that SBS in DVCC is not shared but temps are accessible via VRM? I have multi, BMV, and smart MPPT and if I use DVCC I’m wondering if I have any use for the SBS. Any advice would be much appreciated, thanks!

 

[sunshine_eggo]

Short answer: No use for SBS in VRM.

SBS was my first device, and it is effectively vestigial. It's something I can check with bluetooth when onsite as another datapoint for my temperature sensor "array." It can't interface with a GX device, nor can it be displayed in VRM. Note that the table has a "Temperature on VRM" row, and both SBS are "No."

VRM tracks any of the listed "temperature on VRM = Yes" sensors if present. SVS/SCS/STS under DVCC and the battery monitor selection identify the device doing the sharing to all GX connected devices.

 

[Itsmedp]

Short answer: No use for SBS in VRM.

SBS was my first device, and it is effectively vestigial. It's something I can check with bluetooth when onsite as another datapoint for my temperature sensor "array." It can't interface with a GX device, nor can it be displayed in VRM. Note that the table has a "Temperature on VRM" row, and both SBS are "No."

VRM tracks any of the listed "temperature on VRM = Yes" sensors if present. SVS/SCS/STS under DVCC and the battery monitor selection identify the device doing the sharing to all GX connected devices.

This makes sense, and unfortunately I'm coming to the same conclusion. The system I built out (see attached) utilizes 2 LifePO4 without low temp cutoff. The system is going into my RV pass through storage and I have it built and bench testing now in my garage. I purchased 2 SBS thinking one for each battery and I would use VE.network to manage low temp at least for the SCC. Now, it seems the best plan of action would be to switch to DVCC and use a BMV temp sensor, and share STS to all my devices. I could then use the BMV relay to trigger a heater down the road if I found that compartment heating is necessary.

It seems though, that for a local setup (camping) the SBS could still have some value a dumb Bluetooth sensor, but with the updates to Ruvi integration with GX I'd probably be better off using those.

This post has been really helpful, Ive spent quite a bit of time reading through literature and other posts with no clear answers. Thanks for your reply!

 

[pollenface]

The battery sense also senses voltage at the batteries and tells the mppts to bump up the voltage so that correct voltage is given to the batteries. I like that.

My Epevers are manually bumped up 0.1v to overcome wiring losses.

 

[sunshine_eggo]

The battery sense also senses voltage at the batteries and tells the mppts to bump up the voltage so that correct voltage is given to the batteries. I like that.

I get what you're saying, but this is confusingly worded. The SBS feeds the MPPT the open circuit voltage and temperature. It gives no instructions to the MPPT. It just allows the MPPT to operate with an actual open circuit voltage and actual temperature rather than relying on its own voltage measurement. The MPPT does what it always does, it just uses the SBS voltage rather than the MPPT's current-influenced voltage measurement.

The net results are that it will stay in bulk mode longer and somewhat shorten charge time, and it can engage low temp charge protection or temperature compensation as applicable.

 

[pollenface]

I get what you're saying, but this is confusingly worded.

My wife agrees

 

[Santa Fe Big Sky]

is it better to use the temp sensing capabilities of my Victron Smart charge controller or use a BMS with the temp sensor built in? At this point not using a Victron inverter but….maybe…just maybe in the future.

 

[Rocketman]

You want to use BOTH temp sensors.

The Victron temp sensor (either through a Multiplus, BMV712, Smartshunt, or battery sense), can communicate to the other Victron stuff - (solar charge controllers, Multiplus, etc), so the temperature data is included properly with the charging data (higher voltage on lead batteries when cold, no charge on lithium if too cold,etc)

The BMS temperature sensors is your last defense- you should never need it in a well designed plan, but it will prevent charging a lithium battery when it is too cold and thus destroying it. Belt and suspenders. Both needed.

 

[sunshine_eggo]

^ +1

To elaborate:

is it better to use the temp sensing capabilities of my Victron Smart charge controller

Never. The Victron MPPTs have negligible temperature sensing capabilities. Since the operation of the charger affects its temperature sensor reading, it takes a snapshot of the temperature before it starts charging and behaves as though it's that temperature for the entire day unless power-cycled.

or use a BMS with the temp sensor built in? At this point not using a Victron inverter but….maybe…just maybe in the future.

Most BMS have a temp sensor built in, but not all of them have low temp charge protection.

The cheapest way to feed a MPPT open circuit voltage and temperature is with a smart battery sense in a VE.Smart (bluetooth) network.