Can DVCC be used to stop a Multiplus II from starting when the CANBus battery does not have the right current available due to cold conditions or other state?
I am working on a flow in Node Red to do this which may be enough, but am wondering if there is support for this already? How are you handling scenarios like these?
Many thanks.
Yes/no
if DCL=0 the inverter won't start (-when there is no AC input-)
but in inverter mode, it cannot adhere to DCL values because the inverter cannot control what loads it has to power. if DCL=1 the inverter will start.
So for an off-grid system, system design is very important to not overload the batteries in all conditions..
Many thanks @Daniël Boekel (Victron Energy Staff)
Many thanks and I believe I understand that part.
But the inverter will surely not be able to start when the DCL=1, so what happens then in DVCC
if anything? I assume you are saying it will attempt a start and fail due to low current?
I am generally curious what happens in any real-world scenarios when a CANBus battery will report a low DCL of say =24A and if DVCC will take that into consideration at all?
Also wondering if it will in any way also take CCL into the equation when attempting the start?
I also assume here that I will need to check this manually or via some Node Red flow pre-start
and act accordingly.
Lastly, I assume that the peak surge during such conditions will also be severely limited, even if the batteries are up to spec. for normal and even bad conditions. So how is that handled apart from
looking at the numbers before start? Grateful for any comments.
simple.
-if no AC present / connected (thus: inverter mode)
-only DCL=0 has any effect
This is well known and the reason that the minimum battery size is bigger for off-grid systems vs ESS systems.
the system -cannot- react on other DCL numbers, as it cannot regulate the loads.
CCL does have effect, system will regulate PV power to get to this level.
on ESS (grid connected) systems, low DCL numbers can be met, but there is always a bit of overshoot when loads change, so here also good system design is key.
Many thanks @Daniël Boekel (Victron Energy Staff) appreciate the replies very much!
I believe I my question is more one of proportions I guess.
I have a setup where the loads are not connected until the Multiplus has started so I am only concerned about handling the peak surge of the Multiplus and especially in cold conditions and low DCL/CCL conditions.
According to the Multiplus 48 5000 manual, peak surge capacity is the same as the peak power, so around 9kW. The current battery bank in the installation I have in mind here is rated for 24kW peak but the installation still sometimes has issues with starting if the CCL is low and there is no PV current present. No problems so far when PV current is present. All cables are correct dimensions and the setup works great in every way apart from this start up with low CCL.
I now assume the battery BMS is doing some type of protection that is not published over CANBus.
Will continue research and testing..
good luck!
