I created an eVTOL in X-plane 11.34. With the proper electrical settings, it gets pretty realistic, where big batteries set at the proper capacity give me a moderate range. Now I want to add a Range Extender, for which I use the APU functionality. I can start the APU, but my batteries still show negative amps, meaning they don't get charged. How do I set up the APU such that it can charge my batteries? Or can you suggest another setup?