May I connect an Orion-TR Smart directly to an alternator’s rectified output. No battery there to create smoothed DC. I absolutely cannot put a lead based battery there. Else what sized electrolytic capacitor do I need? Alternator output is maximum 5A RMS. The DCDC charges a 160AH LFP battery. Too small you say? Not if the alternator is running 6 hours a day and I use less than 30AH per 24 hours.
When people gave connected an Orion direct to an alternator they have reported voltage swings as the alternator voltage regulator interacts with the voltage control on the Orion input. Both controllers are trying to control the same voltage by varying the same current. A battery decouples supply and demand current and buffers the voltage / current response. Not saying this will definitely happen but it is seen frequently. Alternator to battery chargers have different input voltage / current control to avoid this.
Can not help on the capacitors size.
Thank you. Is more or less what I expected. However small alternators have no regulation - just magneto coils with very limited magnetic field paths. Will discover soon their behaviour as I will attach various passive loads and look at the signal with a scope.