Volts = Resistance X Current (I amps) Voltage is the potential for charging and current is a better measurement of the rate of charging. The higher the current the faster it is charging, which on a battery usually means it is lower in voltage and charge capacity.

The Battery is pure DC no ripple. The alternator generates 3 phase AC which the diodes and the capacitor in the alternator convert to DC. But it still has a ripple. Electronic Power supplies use all sorts of filtering to generate a pure DC from an AC source (wall plug). The car components are not as critical, until you get to more modern stuff.

Adding all that stuff to the battery is fine, as long as you put relays and breakers for it in the engine compartment bulkhead somewhere. Then you you can just use the alternator side via ignition to run the relays to switch on and feed fan, fuel, water pump, efi etc... from the battery. Use a direct wire from alternator to battery in the engine compartment with breaker if you think you need it to charge battery. If you did this an left amp meter installed in theory you would have half the current flowing through the amp meter. But because of small resistance in the wire to amp meter due to length, gauge and bulkhead connectors, the current takes the least path of resistance and most flow through thicker direct wire from alternator.