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Hi, I have three Victron MPPTs connected to Cerbo GX. It's a 24V system with unmanaged AGM batteries.
My absorption voltage is set to 28.0V.
I need DVCC so that all my MPPTs have the same battery voltage and temperature.
The problem is, that when I turn on DVCC, the MPPT shows a charge voltage of 28.31V. Can someone tell me, where this charging voltage is set, and how can I change it to 28.0V?
Is this maybe because of temperature compensation: -32,4mV/deg (Battery temp: 20°C)?
Thanks
"The problem is, that when I turn on DVCC, the MPPT shows a charge voltage of 28.31V. Can someone tell me, where this charging voltage is set, and how can I change it to 28.0V?"
My understanding is that with DVCC...,, this:-
Inverter/charger (applies to MPPTs only)
The MPPTs internal charge algorithm is disabled; instead it's being controlled by a charge voltage set-point coming from the inverter/charger.
So, if you look via VE Configure at your Multiplus, on the Charger Tab, what are the settings?
How are the 3 networked? VE.CAN? VE.Smart?
What's supplying voltage/current/temperature data?
Whatever the case, triple check that all MPPT settings, including expert options, are exactly the same.
Yes, temp comp is always in play if enabled with AGM if you have a suitable sensor, but -5°C should only yield +0.162V.
14V per 12V is a fairly low voltage for AGM. Are you sure they're not Gel?
Hi, thanks for answering,
well, two of them are on Ve.direct and one is on Ve.can. It is interesting, that this only happens when I enable DVCC. Temperature is supplied by the temp sensor on my Multiplus-II and voltage and current by SmartShunt. I will check all of the settings again, but they look the same to me.
These are my batteries:
https://www.campersolar.ch/shop/ProdukteDetails/SIGA%20SOLAR%20AGM%20Batterie%20230Ah%2012V%20SF230.pdf (six of them, two in series (3x parallel) - 24V)
Can I ask you what would be the optimal Absorption, Float, and Equalization voltage for the system? (The current one was specified by the local battery dealer).
Thanks again,
I can't read that, but these voltages:
Looks like float and absorption.
So, for a 24V system, 29.2 absorption and 27V float. VERY important to confirm that at peak voltage, both 12V are in the 14.6-14.7V range.
AGM should not be equalized, so set to same as absorption and disable auto equal and set equal time to 0.
Well, with two in VE.Direct and one on VE.CAN, I don't see how all three can be coordinating with each other. If you have a VE.Smart network active, I would remove it since all products are connected to the GX.
Do you have the smartshunt set as your default battery monitor?
When you enable DVCC, do you enable, SVS, SCS and STS and specify the MP as the STS source?
OK, I will take a look at it and change the voltage as specified. Battery equalization is already disabled.
The SmartShunt is set as the default battery monitor and yes SVS, SCS, and STS are enabled. Multiplus is selected as STS source.
Everything looks OK, except for the charge voltage on my MPPT. (Image in the first post).
You should be limiting charge current to 195A. Those batteries are 65A max each, and you have 3 strings in parallel. Additionally, since they're not likely perfectly sharing the current between them, you might want to lower that further to 150A.
Again, very important that all 6 batteries are in the 14.6-14.7V range at peak absorption voltage.
What happens when you don't limit managed battery charge voltage? You really don't need this enabled unless you want to further restrict the MPPT and MP AC charger if their voltages are set higher?
OK, I will have more details on the weekend, because I'll be on the premises. Right now I'm 300km away from the system :)
Thanks for your help.
