1. Which relay and control to use?
Various Victron products have functions to automatically signal when to start and stop a generator. Here is advice on when to use which product and method.
1.1. Option 1: GX device like CCGX or Venus GX
When there is a GX device (CCGX, Venus GX, or other) in the system, the best option is to use its Generator Start/Stop mechanism. Its the most feature-rich generator start/stop system that we have to offer. It provides for basic functions as starting and stopping on Battery State of Charge, Battery voltage as well as High load situations. And also has many advanced features, including automatic test runs and silent times.
1.2. Option 2: BMV Battery Monitor
The next most used option is a BMV-700 Battery Monitor or similar model. It can start the generator on low battery voltage and/or low battery state of charge. The BMV uses a dry contact, voltage free relay. See the BMV-700 manual for configuration, and the product data sheets for voltage and current throughput limitations.
1.3. Option 3: Using the relay in the Multis or Quattros
The Multis, MultiPlus-IIs, Quattros, EasySolars and the rest of the VE.Bus family also have Generator start/stop feature with a relay. There are two different ways to configure them:
Generator Start/stop function of the Virtual Switch (recommended)
Generator start/stop Assistant (more advanced / complex)
1.4. Combining the options
Lastly, its of course also possible to combine above mentioned methods, by wiring the open contacts in parallel to each other, or in series, to the Generator.