2500 rpms are highway speeds. High idle boost the rpms in the range of about 1200 on my Sprinter. It is not needed to charge my batteries. If I turn on the engine at normal idle I get charge input to my house batteries. It is just a good practice to according to MB to do so to burn off DEF particles. That’s why they supply a high idle option. Still the practice is to drive at highway speeds for a time after 2 hours of idling.
2015 Advanced RV Ocean One Mercedes Benz Sprinter
Previous Class Bs:
2011 Great West Van Legend Sprinter
2005 Pleasure-way Plateau TS Sprinter