It is all about the internal resistance and admittence of the lifepo battery. Those batteries want a lot of current. The BMS is Lord and Master over those characteristics. The Victron has circuitry to deal with that accordingly. You can get an external BMS that may better regulate the output to input of your alternator. I have a 160 amp alternator with a 30 amp dc to dc. 30 amps limit is a good point when it comes to night driving with everything on. Headlights, windshield wipers,defrost compressor, heater blower on high, all the running lights, stereo cranked up. 30 amps leaves headroom for everything else to run if needed.
