Cerbo GX Manual

Enabling DVCC changes a GX device from a passive monitor into an active controller. The available features and effects of enabling DVCC depend on the type of battery used. The effect also depends on the installed Victron components and their configuration.

Example 1 - Managed CAN-bus batteries For example, in systems with an Managed CAN-bus BMS battery connected, the GX receives a Charge Voltage Limit (CVL), Charge Current Limit (CCL), Discharge Current Limit (DCL) from that battery and relays that to the connected inverter/chargers and solar chargers. These then disable their internal charge algorithms and simply do what they're told by the battery. There is no need to set-up charge voltages or choose the charge algorithm type.

Example 2 - Lead batteries For systems with lead batteries, DVCC offers features such as a configurable system wide charge current limit, where the GX device actively limits the inverter/charger in case the solar chargers are already charging at full power. As well as shared temperature sense (STS) and shared current sense (SCS).

This table shows the recommend settings for different battery types:

Carefully study the following chapters to fully understand DVCC for a particular system.

To enable or disable DVCC, see Settings → DVCC in the menus:

Battery compatilibity

For CAN-bus connected batteries, check the relevant page on the Battery Compatibility manual to see if enabling DVCC has been tested with your battery-type and is supported. If DVCC is not mentioned in notes relating to your battery, do not enable DVCC.

For Gel, AGM, OPzS and other lead batteries, DVCC can be used without any problem. The same is true for Victron Energy lithium batteries with the VE.Bus BMS, the Lynx Ion + Shunt BMS or the Lynx Ion BMS. DVCC is the preferred operating mode for Redflow ZBM2/ZCell batteries using the Redflow CANBus BMS.

Firmware versions

Do not use DVCC in cases where these requirements are not met. In all cases we recommend to install the latest available firmware during commissioning. Once running well, there is no need to pro-actively update firmware without reason. In case of difficulty, the first action is to update firmware.

Required minimum firmware versions:

From Venus firmware v2.40, there will be a warning message 'Error #48 - DVCC with incompatible firmware' when one of the devices has an incompatible firmware while using DVCC.

In case of an ESS System, the ESS Assistant needs to be version 164 or later (Released in November 2017).

Our inverter/chargers and MPPT Solar Chargers use their own internal charge algorithm when in stand-alone mode. This means that they determine how long to remain in Absorption, when to switch to Float, when to switch back to Bulk, or Storage. And in those various phases they use the configured parameters in VictronConnect and VEConfigure.

In certain systems, the internal charge algorithm is disabled, and the charger is then working with an externally controlled charge voltage target.

This guide explains the different possibilities:

Internal

The internal charge algorithm (bulk → absorption → float → re-bulk), and the configured charge voltages are active.

Inverter/charger indicated charge state: bulk, absorption, float, and-so-forth.

MPPT indicated charge state: bulk, absorption, float and-so-forth. (firmware version v1.42 onwards. Earlier versions have a bug that make the MPPT say “Ext. Control” when it is only being current limited; its internal charge algorithm still active.

Inverter/charger (applies to MPPTs only)

The MPPTs internal charge algorithm is disabled; instead it's being controlled by a charge voltage setpoint coming from the inverter/charger.

MPPT indicated charge state: Ext. control.

Battery

The internal charge algorithm is disabled; and instead, the device is being controlled by the battery.

Inverter/charger indicated charge state: Bulk when in current controlled mode, Absorption when in voltage controlled mode. Never Float; even though currents might be low / battery might be full.

MPPT indicated charge state: Ext. control.

These features apply to all types of systems when DVCC is enabled: with or without ESS Assistant, and with lead or other normal batteries as well as when an intelligent CAN-bus BMS connected battery is installed:

8.4.1. Limit charge current

This is a user-configurable maximum charge current setting. It works across the whole system. MPPT Solar Chargers are automatically prioritized over the mains/generator.

This setting is available in the “Settings → “System Setup” menu on the GX device.

Particulars:

1) If a CANBUS-BMS is connected and the BMS requests a maximum charge current that is different from the user-configurable setting, the lower of the two will be used.

2) This mechanism only works for Victron inverter/chargers and Solar 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 MPPTs will be controlled, nothing else. Any other sources will be extra charge current, unaccounted for. Even when installing a BMV or other battery monitor.

3) DC Loads may not be accounted for, unless a SmartShunt or BMV-712 is installed, and correctly configures as a DC load monitor. For example, without the DC load monitor a configured maximum charge current of 50 Amps, and DC Loads drawing 20 Amps, the battery will be charged with 30 Amps. Not with the full allowed 50 Amps. With the SmartShunt configured as a DC load monitor, maximum charge current configured at 50 Amps, and DC system shunt reports a draw of 25 Amps. Then the chargers are set to charge with 50 + 25 = 75 Amps.

4) Current drawn from the system by the inverter/charger is compensated for. For example, if 10A is drawn to power AC loads, and the limit is 50A, the system will allow the solar chargers to charge with a maximum of 60 Amps.

5) In all situations, the maximum charge limit configured in a device itself, ie. the Charge current limit set with VictronConnect or VEConfigure for the Solar chargers or Inverter/chargers will still be in effect. An example to illustrate this: in case there is only an Inverter/charger in the system, and in VEConfigure or VictronConnect the charge current is configured to 50 Amps. And on the GX Device, a limit of 100A is configured, then the working limit will be 50 Amps.

6) DVCC Charge Current Limits are not applied to DC MPPTs when ESS is enabled with Allow DC MPPT to export. This is get maximum output from the Solar panels for export.

This chapter applies to all systems where an intelligent battery BMS is installed, and connected via CAN-bus. Note that this does not include the Victron VE.Bus BMS.

Such intelligent BMS sends the following parameters to the GX device:

For all three parameters, some types of batteries transmit dynamic values. For example they determine the maximum charge voltage based on cell voltages, state of charge, or for example temperature. Other makes and brands use a fixed value.

Here is the page in the menus showing the parameters:

For such batteries, there is no need to wire allow-to-charge and allow-to-discharge connections to the AUX inputs on a Multi or a Quattro.

When inverting, ie in Island mode, Multis and Quattros will shut down when the max discharge current is zero. They will automatically start again as soon as either AC mains returns, or when the BMS increases the max discharge current again.

See previous chapter, “Limit charge current”, the user setting, for details about how the Maximum charge current is used, how it prioritises solar and more.

All above means that setting up charge voltages or charge profiles in VEConfigure or VictronConnect is not necessary, and will also have no effect. The Multis, Quattros and MPPT Solar Chargers will charge with the voltage as received via CAN-bus from the battery.