MultiPlus-II GX

A backlit 2 x 16 character display screen shows system parameters.

The BMS-Can connection allows connecting of compatible 500 kbps CAN-bus BMS batteries. VE.Can products as for example Victron MPPT Solar Chargers, or a Lynx Shunt VE.Can are NOT supported.

Ethernet and WiFi connections allow for local and remote system monitoring, as well as connection to Victron's free VRM portal for long term system performance information.

Houses or buildings with solar panels or a combined micro-scale heating and power plant or other sustainable energy sources have a potential autonomous energy supply which can be used for powering essential equipment (central heating pumps, refrigerators, deep freeze units, Internet connections, etc.) during a power failure. A problem is however that grid connected sustainable energy sources drop out as soon as the grid fails. With the product and batteries, this problem can be solved: the product can replace the grid during a power failure. When the sustainable energy sources produce more power than needed, the product will use the surplus to charge the batteries; in the event of a shortfall, the product will supply additional power from the battery.

Besides the usual uninterruptible output (AC-out-1), an auxiliary output (AC-out-2) is available that disconnects its load in the event of battery-only operation. Example: an electric boiler that is allowed to operate only if the AC input is available. There are several applications for AC-out-2.

The unit can be connected with others and configured for three-phase output. It is possible connect up to 6 sets in parallel in three phases, to a total of 18 units.

The product can supply a huge charging current. This implies heavy loading of the AC input. Therefore a maximum current can be set. The product then takes other power users into account, and only uses 'surplus' current for charging purposes.

This feature takes the principle of PowerControl to a further dimension allowing the product to supplement the capacity of the alternative source. Where peak power is often required only for a limited period, the product will make sure that insufficient AC input power is immediately compensated for by power from the battery. When the load reduces, the spare power is used to recharge the battery.

All settings can be changed with a PC and free of charge software, downloadable from our website www.victronenergy.com. See this manual for more information - https://www.victronenergy.com/media/pg/VEConfigure_Manual/en/index-en.html

The product is equipped with a programmable relay. The relay can be programmed for different applications, for example as a starter relay.

External current transformer option to implement PowerControl and PowerAssist with external current sensing

The product is equipped with 2 analog/digital input/output ports.

These ports can be used for several purposes. One application is communication with the allow-to-charge and allow-to-discharge BMS controls of a lithium-ion battery.

See appendix.

When used in a grid-parallel topology the internal current transformer cannot measure the current to or from the mains. In this case an external current transformer has to be used. See appendix A. Contact your Victron Distributor for further information about this installation type

When solar inverters are connected to the AC-output of the product, excess solar energy is used to recharge the batteries. Once the absorption voltage is reached, charge current will reduce and excess energy will be fed back into the mains. If the mains is not available, the product will slightly increase the AC frequency to reduce the output of the solar inverter.

The ideal solution when the product is part of a hybrid system (AC input, inverter/chargers, storage battery, and alternative energy). The built-in battery monitor can be set to open and close the relay:

Houses or buildings with solar panels or a combined micro-scale heating and power plant or other sustainable energy sources have a potential autonomous energy supply which can be used for powering essential equipment (central heating pumps, refrigerators, deep freeze units, Internet connections, etc.) during a power failure. A problem is however that grid connected sustainable energy sources drop out as soon as the grid fails. With the product and batteries, this problem can be solved: the product can replace the grid during a power failure. When the sustainable energy sources produce more power than needed, the product will use the surplus to charge the batteries; in the event of a shortfall, the product will supply additional power from the battery.

Adaptive 4-stage charge algorithm: bulk – absorption – float – storage

The microprocessor-driven adaptive battery management system can be adjusted for various types of batteries. The adaptive function automatically adapts the charging process to battery use.

The right amount of charge: variable absorption time

In the event of slight battery discharge, absorption is kept short to prevent overcharging and excessive gas formation. After deep discharging, the absorption time is automatically extended in order to fully charge the battery.

Preventing damage due to excessive gassing: the BatterySafe mode

If, in order to quickly charge a battery, a high charge current in combination with a high absorption voltage has been chosen, damage due to excessive gassing will be prevented by automatically limiting the rate of voltage increase once the gassing voltage has been reached.

Less maintenance and aging when the battery is not in use: the Storage mode

The Storage mode kicks in whenever the battery has not been subjected to discharge during 24 hours. In the Storage mode float voltage is reduced to 2,2V/cell to minimise gassing and corrosion of the positive plates. Once a week the voltage is raised back to the absorption level to 'equalize' the battery. This feature prevents stratification of the electrolyte and sulphation, a major cause of early battery failure.

Battery voltage sense: the correct charge voltage

Voltage loss due to cable resistance can be compensated by using the voltage sense facility to measure voltage directly on the DC bus or on the battery terminals.

Battery voltage and temperature compensation

The temperature sensor (supplied with the product) serves to reduce charging voltage when battery temperature rises. This is particularly important for maintenance-free batteries, which could otherwise dry out by overcharging.

Victron LiFePO4 Smart batteries

Use the VE.Bus BMS

Lynx Smart BMS - This BMS is recommended when also using a GX device in the system. It is connected via the VE.Can bus interface. Note when using this BMS set the Remote Mode to Remote on/off when commissioning the product in VictronConnect.

SmallBMS - This BMS is connected using the allow to charge, and allow to discharge contacts from the Victron smallBMS to the I/O connection port. Note when using this BMS configure for Remote Mode 2-wire BMS when commissioning the product in VictronConnect.

Compatible BMS-Can Lithium Batteries

Compatible BMS-Can lithium batteries can be used with MultiPlus-II GX however it is a requirement that those batteries to be connected via the BMS-Can port of the GX device (such as the Cerbo GX), and not to the MultiPlus-II GX communications interface directly. See the Victron Battery Compatibility Guide for more specific information.

Please see https://www.victronenergy.com/live/battery_compatibility:start

Our book 'Energy Unlimited' offers further information on batteries and battery charging, and is available free of charge on our website: https://www.victronenergy.com/support-and-downloads/technical-information.

For more information on adaptive charging, please also refer to the General Technical Information on our website.

Victron provides a comprehensive Online Training program via the https://www.victronenergy.com.au/information/training web portal. Successful completion of this training should be considered essential for system designers and installers, and is recognised with a graduation certificate.