Limiting the AC input of a Phoenix Smart Charger in parallel with a MultiPlus Compact

In a previous article I described the electric installation in our Toyota HiAce with a 24V battery and a Victron MultiPlus Compact 24/1600/40-16. At that point one piece was still missing: the Phoenix Smart IP43 Charger 24/25. It finally arrived this weekend and so it was time to install it; and configure it – which is normally not something worth going into lengthy detail.

However, in this case we wanted a kind of “special” setup which included the use of MultiPlus Assistants. So, in this article I will quickly describe what we wanted to achieve and how we implemented it.

In general, when connected to shore power we want to be able to limit the AC current drawn from the shore power. This is easily accomplished by setting a limit on the MultiPlus itself – or, as in our case, via the VE.Bus Smart Dongle. Though the Phoenix does have a VE.Direct interface and is able to be connected to a GX device, in our setup we did not want to use a GX device. So, essentially the Phoenix can only be controlled via Bluetooth and the VictronConnect app. But configuring the AC input limit on two devices (Phoenix and MultiPlus) is not only a nuisance from a usability standpoint, but also error-prone as one (or at least we) tend to forget things quickly. So, a different and better solution was needed.

Enter the MultiPlus Assistant in form of the Programmable Relay. With this, we can configure the built-in relay of the MultiPlus to open and close based on the availability of an AC input.

Note: we have to disable “Virtual Switch” in the MultiPlus to be able to use the MultiPlus Assistant.

The Phoenix has a Remote Input connector, that can be used to stop charging when the connection is “off”. So in our case, we enabled two Programmable Relay assistants:

1. Programmable Relay, NC – On/Open
   After 5 seconds of AC input on the MultiPlus the relay is opened.
2. Programmable Relay, NC – Off/Closed
   After 1 second of no AC input on the MultiPlus the relay is closed (which is the default state).

The wiring is as easy as to connect:

• MultiPlus Relay COM < — > Phoenix Remote Input L
• MultiPlus Relay NC < — > Phoenix Remote Input H

Note: on this page you find a description where the relay is located in the different MultiPlus models.

Below you find some screenshots with the configuration in VE Configure:

So, five seconds after the MultiPlus has power via AC input it will open the relay which in turn will enable the Phoenix to start charging.

One second after AC input is gone the MultiPlus will close the relay so the Phoenix will stop charing (if it was charging at all).

The AC input of the Phoenix is connected to the AC output of the MultiPlus. So, when there is a AC input limit configured on the MultiPlus (such as 3A @230V) the MultiPlus and the Phoenix will not be able to charge with more than 3A. And from the MultiPlus perspective, the Phoenix is just an arbitrary consumer.

This can lead to some undesired behaviour if we were to limit the AC input to e.g. 1A. In this case, the MultiPlus would – when in Inverter mode – draw from the battery so the Phoenix could charge the battery. perpetuum mobile … ? And when the AC input is gone, this means that for roughly one second the Phoenix will also charge form the battery. But this is something I can live with easily.

And if we really had a very low power AC input (of e.g. 1A) we can still unplug the remote input and force the Phoenix not to charge. Or manually switch the MultiPlus to Charger mode only.

For us this is a usable solution without the need for multiple configuration changes nor the presence of a GX device.