Victron Low Temp Cutoff

[atatistcheff]

I'm putting together my vehicle mounted system and want to make sure I buy the right accessories. I'm using a Victron 100/20 MPPT and a 500A bluetooth Smartshunt. Both are located with the batteries (LiFePO4 from Li Time). My question is, what is the best/cheapest/simplest way to add a low temp charging cutoff for the PV charging? Seems like there is the Smart Battery Sense but that uses a bluetooth connection to the MPPT which isn't really needed here since everything is in the same spot. Perhaps a wired sensor for the Smartshunt? Just looking for options/opinions before I buy something. Thanks!

 

[atatistcheff]

Ok looking closer at the wired temperature sensor I see that it works with the smartshunt as well. So let me modify the question a little. That silly little wire with temp sensors costs $32 and the bluetooth smart sensor is $40. Is there an advantage to getting the bluetooth sensor? I feel like it's kind of a ripoff to spend $32 for about $1.00 worth of hardware.

 

[featherlite]

what is the best/cheapest/simplest way to add a low temp charging cutoff for the PV charging

I would think the best/cheapest/simplest way would be to use the Smart Battery Sense

 

[Q-Dog]

either solution will work. $32 is less than $40.

 

[sunshine_eggo]

If you have any desire to EVER use a GX or a VenusOS RPi, the SBS will NOT work with it or VRM. You must use the BMV temperature probe.

The SBS will work behind the scenes in a VE.Smart network, but its information can't be passed to any device outside the VE.Smart network like an inverter.

 

[featherlite]

The SBS will work

Are there any advantages of using a Smart Battery Sense over the BMV temperature probe, other than the fact that the BMV temperature probe uses up the Aux port on the shunt?

 

[sunshine_eggo]

Are there any advantages of using a Smart Battery Sense over the BMV temperature probe, other than the fact that the BMV temperature probe uses up the Aux port on the shunt?

One might believe the side of the case is a better representation of the temperature vs. the terminal?

 

[atatistcheff]

So I'm still trying to wrap my head around how this works. In the case of the SBS, it communicates directly with the MPPT to shut down the charging when the temp is too low. For the wired temperature sensor, this connects to the Smartshunt in my case. I'm assuming that the Smartshunt then communicates with the MPPT via bluetooth? I am leaning towards the SBS since it does give more options for where to place it.

 

[sunshine_eggo]

The MPPT is configured to stop charging below a certain temperature.

Either communicate their temp reading to the MPPT via a VE.Smart network (bluetooth).

EDIT:

Smartshunt provides:
Current, voltage and temperature (if probe attached) data.

SBS provides:
Voltage and temperature data.

So BOTH give the MPPT an open circuit voltage reading to improve charging and accuracy. The shunt provides the charge current as well. If you are using tail current for absorption termination, the MPPT will use the shunt reading instead of its own current reading. This improves charge termination if you're also using solar for loads.

 

[740GLE]

Don’t the li time batteries have low temp protection as well?

I’d much rather trust an internal battery temp sensor as cells maybe cold soaked, where air ambient temp rises much faster.

Or are you looking for double protection?

 

[atatistcheff]

Don’t the li time batteries have low temp protection as well?

I’d much rather trust an internal battery temp sensor as cells maybe cold soaked, where air ambient temp rises much faster.

Or are you looking for double protection?

Sadly many Li Time batteries don't have low temp protection.

 

[Pi Curio]

The MPPT is configured to stop charging below a certain temperature.

Either communicate their temp reading to the MPPT via a VE.Smart network (bluetooth).

EDIT:

Smartshunt provides:
Current, voltage and temperature (if probe attached) data.

SBS provides:
Voltage and temperature data.

So BOTH give the MPPT an open circuit voltage reading to improve charging and accuracy. The shunt provides the charge current as well. If you are using tail current for absorption termination, the MPPT will use the shunt reading instead of its own current reading. This improves charge termination if you're also using solar for loads.

I wonder if you happen to know if both, the Smartshunt and SmarBattery sense can be connected to a single mppt? Would there be some sort of conflict in MPPT readings of voltage from smartshunt and the sbs at the same time?

I also have the smartshunt and just received the sbs and worried there might be an issue if I connect both to the MPPT. I bought the SBS because it makes sense to have temperature readings at the battery case, not the terminal.

Appreciated.

 

[Rocketman]

I will pop in with my experience. I built my own battery for my MotorHome. It is basically outside in a metal box.
I have used the BMV712 with the battery temp sensor. With a heat pad and some insulation around the battery. Some nights it has been in the mid-20’s - the battery stayed about 40F. (Any colder and the wheels on the MotorHome move us to a warmer place).

I used the VE.Smart Networking (Bluetooth) and it works ok, but the DVCC on my CCGX (older product- Cerbo is the new product) works better. (Better is probably because of my setup - Victron stuff is all over in different places and far from each other - so I have all kinds of voltage drop issues).

I set my mppt temperature cutoff at 40F - I figure that will give the battery time to warm up if it is cold soaked.

Good Luck

 

[sunshine_eggo]

5. Limitations

www.victronenergy.com

5. Limitations​

• The maximum number of devices which can be connected on one network is 10.
• VE.Smart Networking is designed for small systems which do not have a GX device - such as a Color Control GX or Venus GX - controlling the chargers (e.g. in an ESS system) - See FAQ Q5. In systems which the GX device is used for logging purposes only, VE.Smart Networking can be used to allow chargers to synchronise, or even receive information from sensors. Keep in mind that if, for some reason, the same information (i.e. voltage sense) is being received by the charger over BLE and VE.Can/VE.Direct, the information coming over BLE (through VE.Smart Networking) will be ignored.
• The transmitter range will be found to be the same as the Bluetooth range - as experienced when connecting a device to VictronConnect.
• It is not possible to measure multiple battery temperatures/voltages/charge currents: only one Smart Battery Sense, or one BMV can be used in a system. Having multiple sensors connected to different batteries can lead to charging issues as overcharging or heating up the batteries. Always make sure to have your sensors/chargers on the VE.Smart Networking connected to the same battery. If, by accident, two or more sensors (e.g. Smart Battery Sense and/or BMV) are connected to the same VE.Smart Networking, a priority mechanism is used to decide which battery temperature, battery voltage and battery current should be used by the charger. The priority mechanism is first based on the type of sensor (e.g. BMV has higher priority than the Smart Battery Sense), and second based on the serial number of the sensor. At the end, only one information will be used by the charger.

 

[Tomthumb62]

Just throw a Blue Steel at it and it’ll cut off at the correct temperature. No Bluetooth needed.

BS>BT

 

[sunshine_eggo]

Magnum > BS

 

[pollenface]

Are there any advantages of using a Smart Battery Sense over the BMV temperature probe, other than the fact that the BMV temperature probe uses up the Aux port on the shunt?

Cheaper if you don't want smart shunt.