With a large Magnum Inverter supplying power to an RV is a large generator also needed if charging is done through the Inverter. When running the charger is the inverter not used and the transfer switch is closed. In this case, a lot of problems exist when using a small generator or limited shore power. Overload of the generator if appliances are used or very limited charging. To get around that issue have we now added a charger directly to the battery system. That allows direct charging on the battery without using the charger in Magnum Inverter.
This has many advantages that with the right charger can the generator be loaded at a constant high load and no additional load can occur based on what we use in the RV.
With the Tesla modules floating at 24.1 Volt can a charger not be purchased cheaply to handle this. But two relays and a Under Voltage controller can easily control this, the benefit is also having a display showing the current battery volt.
An Under Voltage Controller is working the opposite way opening the circuit when voltage is too low. But by using a Relay with both the Normal Open and Normal Closed pin is it easy to reverse this. Ensure you buy 24 Volt relays and the small relay must have the 87a connector.
This diagram shows the components and wiring between them.
We really never need a generator, but this simple setup for less than $300 allows running the generator without the risk of overcharging the Tesla Modules.