Please make it possible to use a Smart Shunt and BMV-700 usable as controlling BMS in Venus OS (DVCC->controlling BMS)
Background: Batteries with not supported BMS can use BMV-700 or Smart Shunt to controll the system.
This is not possible as a shunt cannot send CVL, CCL or DCL to the system which is required for the battery to manage the chargers.
It is also restricted to CAN comms, which shunts don’t support.
Shunts can be references for DVCC but cannot be used for battery management.
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Why not? It would be possible to store a characteristic curve for CVL, CCL or DCL in the Shunt Settings.
And the restriction to CAN is also a software problem, so far I can see it.
So for me it would be a feature request.
CAN is a hardware problem.
Charge limits from a BMS are largely influenced by individual cell Voltage readings, which is why a BMS is connected to each cell.
A shunt doesn’t see any of this, a generic curve is also pointless due to the flat voltage curve of lithium.
Beyond that, the hardware on a shunt is very limited and, even if there was a will to do such a niche development, the hardware wouldn’t cope.
Nick has a point. Would not trust a safety device incapable of detecting all the different internal problems that might happen inside the battery’s internal components. LiFePo4 is a safe chemistry, but nothing is 100 safe when it comes to internal failures and fire risks.
A shunt and a bms are two totally different things in any case.
You can set it as the system battery monitor.
Settings - system set up- battery monitor.
But this will not stop charge or discharge if there is an internal problem. For that you need a can managed battery
You can node red something for CC based on bank voltage. But that is not going to be enough for internal battery protection
As an it professional and electrical engineer, i see things somewhat differently. The main point here is that the shunt can gives the system the specifications for charging and dischanging and the point of switching off. I can set all parameters in every device that is connected to an GX or, alternatively, I can set it for the shunt and the system follow the settings in the shunt. And at this point it makes no difference whether the shunt is connected by CAN or otherwise. (At most it can be a driver problem.)
From a GX controlling point of view, there will be no difference between a large bank of battery cells with each having controlling hardware or a shunt that represent one great cell.
(As i wrote in the first post, it is only about the control of the system, not about extended protection mechanisms for the battery.)
But I can also understand that it might be uninteresting or too complex for victron to program such a feature.
I think you are missing some of architectural/system specifics that make these systems work.
There is nothing wrong treating a lithium battery as a “dumb” bank like lead acid.
The only reason you have management is for fine control of individual cells, which in the lead acid world would use individual temperature sensors, mid-point voltage measurements between batteries and external balancers.
What you are asking for is simply not possible on a shunt, for a broad variety of reasons, nor would it make much of a difference if it were.
This can nonetheless, be easily coded in nodered to control charge current based on voltage.
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What architectural/system specifics do you think I am missing?
I would not replace a BMS by a shunt.
My batteries have a BMS. My system works several years and we have special conditions (working range between -15 and 40 degrees Celsius), so my battery and the BMS was self constructed. In my system I have 5 MPPTs with the same settings, but the not have the same working points. Some switch form bulk to float wheter other work in bulk mode at the same point. The are all voltage controled by there own. I think the reason are different voltage drop on the line and internal electronics.
In such a case it would by great to have one point that can control the whole system, so every thing act together.
I make this suggestion because I thought that there are more people who can benefit from this.