Suplementing a pair of Quatros running DVCC with a Skylla-i charger?

Q&A and troubleshooting
, , , ,
1

I have a new NG Battery/BMS system that includes an Ekrano GX and a pair of Quatro 5KW inverter/chargers. They are configured to run DVCC.

I would like to add some additional charging (only….not inverting) capacity to the system because if have a large (25KW) generator and I could charge the 1800AH battery bank more quickly as well as load the generator more effectively if I add additional charging capacity.

My plan was to add a pair of Skylla-i chargers, but I realize that they do not implement DVCC. I found the following statement on the Victron website:

https://www.victronenergy.com/media/pg/Cerbo-S_GX/en/dvcc—distributed-voltage-and-current-control.html

  1. This mechanism only works for Victron inverter/chargers including Inverter RS, Multi RS, Solar chargers incl. MPPT RS and Orion XS DC-DC battery chargers. Other chargers, such as Skylla-i’s are not controlled and also their charge current is not taken into account. The same applies for devices that are not connected to the GX device, such as an alternator. Worded differently: the total charge current of the inverter/chargers and all MPPT solar chargers will be controlled, nothing else. Any other sources will be extra charge current, unaccounted for. Even when installing a BMV or other battery monitor.

I have two questions:

  1. What are the implications of the “uncontrolled” Skylla-i chargers if they are running in parallel (charging the same house bank) as the Quatros? They would be connected to the Ekrano by VE.can, but they don’t implement DVCC. The pair of Quatros and even a pair of Skylla chargers could only produce a maximum of 440 amps of charging current and my system can handle this without issue. But will the Skylla’s “cooperate” with the Quatros at least during the bulk phase when more current is the most helpful? What are the risks of this configuration?
  2. Are there any plans to add DVCC capability to the Skylla charger family? I’m not sure if it’s just a firmware thing or if additional hardware is required.

Thanks!

Mark

2

We have two installs with Skylla-i and Quattro with DVCC on one install, two Quattro”s with DVCC on another. Both are connected via VE-Can.

Works well but there are a few odd BMS alarms on the cerbo, The Skylla does most of the work and the Quattro fills in the rest until the current limit is reached.

3

Consider adding one or two Multi’s to your system and run them in charger only mode. Use an MK3-USB adapter to connect them to the Ekrano and use a recent version of VenusOS that supports doing this. The additional Multi’s will be controlled by DVCC. This is a simpler and supported solution.

Alternatively, use the Skyllas if you prefer and set the absorption and float voltages the same and 0.5V lower than the max bulk/absorption voltage your batteries will do. You can adjust this voltage delta over time. As the batteries get close to full charge, the Skyllas will provide less and less charge since their voltage will approach and then be below the batteries. You can power the Skyllas from the AC-Out-2 on the Quattros and they will automatically turn on/off as the generator turns on/off.

Personally, I prefer the first method if it’s feasible for you.

Good luck!