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CAN integration with Victron equipment

I am in the process of fitting x8 Eve 280 amp/hr LifePo4 cells into my motorhome.
I intend to have x4 groups of( x2 cells each in parallel ) then series connect the x4 groups to give > 12 volts. 560 amp/hr.
I have found info on your Tao BMS.  Looking at all the specs it seems to be very good product.
I will be using Victron equipment for charging LifePo4.

1-- Victron Smart DC/DC charger ( From alternator )
2-- Victron Smart MPPT solar charger ( x4 100 watt panels )
3-- Victron Smart MPPT solar charger ( x1 250 watt panels
4-- Victron Smart AC to DC mains charger.

If I use the Victron Cerbo GX Touch screen with VE can bus / smart shunt how does the Tao BMS control the shutdown for over / under voltage from batteries / charging units. ( Can Bus )
Is there any advantage in using the Cerbo system over your Tao touch screen.
I understand the Tao system has output relays that can be used for over / under voltage shutdown from batteries / charging units.
Before I retired my trade in New Zealand was industrial / electrical / instrumentation / controls tech.

Your thought's on the best way forward please.

G.

Good idea to standardize on Victron equipment so that the Cerbo GX can control all of them via CANbus.

The Monitor for TAO BMS connects directly to the Cerbo GX via CANbus.  It sends to it:

  • the battery status: voltage, current, temperature, SOC, SOH
  • the instructions on charge current / voltage (same for discharge if you have an inverter)

The BMS sends CANbus instructions based on the triggers that are defined.  See the BMS manual to understand the trigger definition - they are thresholds (high or low) based on cell voltage / temperature and/or state of charge.  For each of these triggers you define the max charge voltage and current.  These are sent to the CerboGX when a threshold is reached.  To stop the charge the current instruction is set to zero.

You can also set the Cerbo GX to use the data from the BMS as THE reference for all Victron equipment - so no need for a Victron shunt or temperature sensor.  On my boat I do not have the Victron screen and do not see what it would add considering that I can access it via WiFi on phone or tablet...  and I never need to get to that information once the system is setup.  The Cerbo screen might be useful is you connect other sensors to the Cerbo - like engine controls, tank gauges...

BMS outputs: yes, there are 6 of them.  Each of them can be linked to one or more triggers described above.  They can command contactors and also be used to directly remote command each Victron equipment.  Even if you use CANbus, I recommend using the remote command... just in case the Cerbo GX is down or other CANbus issues.

Best way forward: read both the BMS and Monitor user manual to understand the features and decide how you want to use them.  Then draw a schematic of your installation...  Do not hesitate to post questions on the Forum if there is something you are unsure about, or just would like to validate your plan.

Philippe

Instructions have now been published on setting up the BMS and the Victron Cerbo GX so that they can communicate over CANbus.  See the link below

CANbus setup for Victron products

andreshs1 has reacted to this post.
andreshs1

Hi @philtao

 

Sorry to bother you again

Today I have been trying to do the CanBus setup, wires connected (white/brown 7 to H and brown 8 to L). This cable is connected to the VE.Can port of the Cerbo GX, with a network terminator at the other end (I saw that the Tao Monitor comes by default with the jumper, correct?)

now, the problem I have is that when I open the setup screen in the Cerbo GX, under batery monitor I cannot see the option for CanBus. 

Any hints on where I should look?

Regards
Andres

It sounds like you have the proper termination resistors at both ends.

Using a ohmmeter have you checked that you have the right wires connected to pins 7 and 8?

Is CANbus enabled on the BMS Monitor side, and do you have the same CANbus speed on the Cerbo GX and the BMS? usualy 250 or 500 kbit/s

Do you have the 5 "SMA Victron" messages enabled in the BMS?  The Cerbo GX will not detect the BMS if the message id "35A" is not enabled

On the Cerbo menu screen for the VE.can port, select the last option "network status".  If there is no traffic the BMS may not be sending anything.  You can restart the BMS Monitor (just in case!) and check the CANbus parameters.

Let me know the outcome.

Hi @philtao

 

OK, the problem with my setup was that I could not do step 1 of the installation guide, as the option to select on the "Battery Monitor" the "CAN-bus BMS battery on CAN-bus" option was not available. It was only after I changed the Can-Bus profile to "VE.Can & CAN-bus BMS" that this option became available.

I have tested the triggers with the fault simulation and It all seems to be working well now, thanks again 🙂

Regards

Andres

philtao has reacted to this post.
philtao

Hi @philtao

I am sorry to keep bugging, but there seems to be something wrong with my configuration

After enabling the Can-Bus, I do not get the batteries to charge anymore

Today I am running the generator, as I wanted to be able to balance the cells as per our other discussion, but the charger is not sending current to the batteries, and while the generator is running then the solar charger is also off

I have double checked the instructions on the installation guide, and it all seems correct

Any ideas where I should be looking at?

Regards

Andres

 

I

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Hi Andres,

Can you post the following screen captures:

  • BMS / Monitor configuration: CANbus voltage and current limits
  • Cerbo GX / Venus: DVCC setup screen 
  • Cerbo GX / Venus: actual voltage and current limits (Device list -> CANbus BMS battery -> Parameters) 
andreshs1 has reacted to this post.
andreshs1

Hi @philtao

 

Very strange, I have done a Monitor Firmware update and now I can see the chargers working.

I have also tried changing on the fly the CCL and I can see the changes in the Cerbo in real-time

One last question, my batteries are new, yet, today the internal resistance has been jumping to 0.37~0.43mOhm. I have now reset it to nominal and I will charge the batteries as per your userguide to calculate the correct resistance

 

Regards

Andres

Maybe there was an error on the CANbus.  When the Monitor restarts after the firmware update it reinitialzes the CANbus and clears any previous error.

The cell resistance varies with the state of charge.  The BMS will only try to calculate the cell resistance if the SOC is between 35% and 70% .  You should therefore have the battery at about 50% SOC when following the manual instructions to force calculation of the cell resistance.

Note: as the cell resistance varies with the SOC and temperature, the calculated value will fluctuate over time.  The displayed resistance value is the average of the last ten measures.

andreshs1 has reacted to this post.
andreshs1