Installation guide to connecting a Redflow battery array to a Victron Energy system

This is a step-by-step guide to connecting a set of Redflow ZCell/ZBM2 batteries to an energy system using Victron Energy components.

This is a differences guide only!

It assumes you already know how to set up a working Victron Energy system (and how to set up and use ESS if it is an on-grid system). 

The installer must is already be trained in the design and installation of Victron Energy based systems. If this is not the case, they need to undertake Victron Energy system training first.

Redflow is not a Victron Energy training provider - Redflow's own training is differences training (as is this installation guide). It assumes you, as an installer, already know how to install a Victron based energy system based around a smart (e.g. Lithium and Lithium BMS) based battery - or at the very least using a conventional Lead-Acid battery.

Prerequisites

• The ZCell physical installation has been done in accordance with Redflow guidelines and training
• The ZCell BMS has been physically installed and powered up (see the BMS guide section for physical BMS interface details)
• The BMS is successfully communicating with the ZCell cluster using CANbus [ see this article for instructions on how to do this ]
• For an on-grid system - that the system has been designed, wired and intended to be configured in accordance with the Victron Energy ESS Design and Installation Manual
• That all firmware and software elements have upgraded to at least the minimum required versions (as noted below) and preferably to the latest production releases of all components concerned

You should also re-check and further update these system components at regular intervals. These system elements and their functionality and feature sets are regularly improved over time by both Redflow and Victron based on learnings obtained and issues resolved in the field.

The system components to check - and the recommended minimum firmware versions for each - are as follows (as at September 2019):

• CCGX / Venus GX : Version 2.23 or later : check the Settings->Firmware page
  • Note: The GX platform auto-updates itself by default
• MultiGrid/MultiPlus/Quattro flash firmware : Version 462 or later
  • These devices should be upgraded using the Victron VE.Flash tool.
  • Flashing the firmware removes all 'Assistants' and also removes any multi-unit cluster configurations, so these need to be re-loaded following any flash updates
• MultiGrid/MultiPlus/Quattro systems need to be running the latest ESS Assistant (only required for on-grid deployments):
  • See https://www.victronenergy.com/live/assistants:how_to_update_an_assistant
  • The Victron VE.Configure tool automatically downloads the latest assistant versions
• MPPT DC solarcharger units need to be upgraded to their latest firmware release using the VictronConnect tool or online using the VRM portal 'Device List' remote upgrade function
• The Redflow BMS needs to be running the latest release (1.7.0 or later).
  • Use the Tools->Upgrade BMS page to check and upgrade the BMS 
• ZCell batteries should be running the latest released battery firmware (32.18.00 or later).
  • The latest recommended battery firmware is carried inside each BMS software release
  • If battery firmware needs updating, a yellow caution triangle will be shown beside the firmware version number on the main BMS status page
  • Use the Tools->Upgrade Battery menu item to upgrade the battery firmware if required

Solar AC Inverter Placement in a Redflow system

There is an important constraint for the deployment of AC solar inverters in a system using Redflow batteries.

The AC solar inverter(s) must be installed on the 'grid' (input) side of the Victron Inverter/Charger system(s), and not on the AC output side of those units. In other words, AC solar should not be installed in the location marked with a red X in this diagram:

AC Solar inverters can be deployed without constraint on the AC input side and/or using DC MPPT's. However, as for all ESS installations, if there is any AC solar on the 'input' side, then an ESS compatible grid meter must also be installed.

The reason for this constraint is that when the Redflow batteries are completely full, they electrically block any further charging energy from entering the battery. If there is a grid power failure when the ZCell batteries are full and when the system is exporting solar energy to the grid, the lack of ability for the resulting transient energy surge to be absorbed by the battery system results an AC voltage surge that will shut down the inverter/charger(s) and that may even damage connected AC appliances.

So - to be clear - the Victron "Factor 1.0" rule (for installing 'load side' AC solar inverters) does not apply with a Redflow system - where there can be no 'load side' AC solar at all.

There are ways to work around this constraint - for sites that wish to have AC solar on the 'load side' for solar support during long outages -  but they are complex and they require additional wiring and hardware, and they are outside of the scope of this document.

The recommended way to provide for this outcome (continued solar site support during extended grid outages) is to use DC MPPT's as the source of solar energy for the system, that can be augmented (if desired) with additional AC based solar placed (only) on the 'input' side. 

Install and configure ESS for use with ZCell systems (on-grid installations only)

Note: ESS is not required and generally not installed in off-grid installations.

Use VE.Configure to load in the "ESS Assistant" to your Multi/Quattro just as you would for any other ESS based Victron installation, in accordance with:

https://www.victronenergy.com/live/ess:design-installation-manual

When you run VE.Configure, please allow it to update to the latest Assistant versions (if offered).

As of April 2020, Victron Energy directly support the Redflow ZBM2/ZCell battery type in the ESS assistant.

When you run the ESS Assistant, just select the Redflow option on the page shown below, and all of the necessary voltages will be configured by default to the appropriate values for Redflow battery systems.

It is important to select the Redflow Battery type in the ESS Assistant, or the system may not operate correctly.

Notes: 

1) When you are asked to specify the battery system capacity (in Ah) by the ESS assistant, enter a value based on 200 Ah per ZBM2/ZCell battery. For instance, in a 2 battery system, you would enter 400 (Ah). 

2) Providing you use the CANBus interface from the Redflow BMS to the Victron Energy GX system in your site, there is no need to adjust any other charger voltages or battery related settings in VE.Configure, because these are all set dynamically via the CANBus interface; Just set your 'grid code' appropriately (if your installation is 'on grid'), load the ESS Assistant (if needed, as above) - and 'that is it'

Enable the Victron DVCC mode (for all ZCell systems)

The Dynamic Voltage and Charge Current mode is designed for 'smart' battery systems that communicate via CANBus from a BMS to the CCGX (such as the Redflow BMS and ZCell units)

DVCC is appropriate for and recommended for use with both On-Grid ESS and Off-Grid (non ESS) Victron Energy systems. 

DVCC enables the system-wide dynamic control of current and voltage limits based on BMS information.  It is  a major enhancement in how Victron Energy systems operate.

The charging cycle for batteries is no longer based on the old 'lead acid' notion of initial/bulk/absorption phases. Instead, the charging control systems enage (and switch between)  Constant Current (CC) and Constant Voltage (CV) target modes, as DC bus conditions change.

The DVCC control mode is ideally suited to the operation of smart batteries with near-linear charge/discharge characteristics such as the Redflow ZCell.

Note that on-screen displays when DVCC is operational show 'Absorption' when in CV mode, and 'Bulk' when in CC mode.

Note: Older model Victron Energy based MPPT solarchargers (that don't have VE.Direct connection paths) do not support DVCC. All the VE.Direct based units do support it. Only use VE.Direct MPPT models for new installations.

With those pre-requisites undertaken, and with CANBus communications from the BMS to the CCGX screen already operating (as per other knowledge base articles), turning DVCC on is easy: 

• In the CCGX Setup -> System Settings menu, turn on DVCC (as per the screen shot below)
• Then under the DVCC switch, please turn off SVS (This option will appear once you enable DVCC):

Note: SVS is 'shared voltage sense' - an intended improvement to the way the Victron Energy system senses bus voltage. However, SVS is (at the time of writing) incompatible with the ZCell battery and BMS operating cycle and- hence ... just turn it off.

If SVS isn't turned off, the system may 'hunt' in terms of target voltage and current over time and may be unable to smoothly bring a ZCell through its post-maintenance pre-charge phase to start to charge it up again.  Leaving SVS on may also lead to system voltage surges during substantial changes in bus operating conditions over time, with the potential for intermittent ZCell protective shutdown/restart cycles occurring as a result. 

Other Post-Installation Settings to adjust in a Redflow installation

ESS MinSoC

Note that for correct system operation, the Settings->ESS menu 'Min SoC' value must be set to 0% in single-ZCell systems.

This value can, if desired, be set to a non-zero value (but generally not above 50% in multi-ZCell systems). This is to ensure that it is possible for the discharge/maintenance cycle required by the ZCell to operate properly. 

In a single ZCell system where MinSoC is desired to be non-zero, consider instead the use of the CCGX 'Scheduled Charging' feature (a sub-menu under the ESS Menu) to perform a baseline charge once a day at a time that still allows for the battery to discharge for maintenance successfully when required.

ESS Operating Mode

It is important to ensure the Settings->ESS Menu 'Operating Mode' is set to 'Optimised (Without BatteryLife)' and is not set to 'Optimised (With BatteryLife)' 

The Victron Energy 'BatteryLife' feature is incompatible with the need to fully discharge the system periodically in a single ZCell environment.

In a multiple ZCell installation, BatteryLife may be able to be used, but Redflow recommends that BatteryLife is disabled in all Redflow installations for various reasons reasons, including to ensure that battery maintenance cycles can be performed efficiently.

Quattro/Multi 'Low Battery' Alarm 

You should disable the 'Low Battery' alarm for your Quattro/Multi environment to avoid swamping your CCGC display with spurious Low Battery alarm notifications each time your system is performing battery maintenance.

You can find this setting by selecting your Multi/Quattro on the CCGX menu and navigating to the 'Alarm Setup' sub-menu, and then setting the first alarm in the list, 'Low Battery', to Disabled

System Timezone

That the CCGX picks up NTP based (Internet-synchronised) time automatically, but you do have to tell it which timezone it is physically installed into.The system timezone should be set correctly under the Settings->Date & Time menu, to obtain accurate (local time) based logging information and so the time shown on the on-screen CCGX display is correct. 

In case of problems

First, do check to make sure you have made all the setting changes noted above!

Next, you can try upgrading firmware (including in the Multi/Quattro and in the BMS) to the latest released versions first. A very wide variety of issues are dealt with and handled in improved ways in newer software releases.

Also do check the diagnostic advice under the 'Victron Energy Troubleshooting' section of this Guide Centre - as a number of common operational issues and their solutions are covered there.