And then there's battery charge rate...
The primary concern though, is that the consumption of power is a necessary thing, as the OEM alternator is a permanent-magnet stator system, controlled by a shunt-regulator. As the alternator spins, magnets induce potential on the windings, which is rectified, and sent out to loads... BUT...
When there's substantial current load, the stator's output voltage is limited by stator winding impedance (R and Z). Resistance being linear, if the stator resistance is high, then R ohms will determine what the limit of output current IS. Z is frequency-variable. if the impedance of the stator coils is high, it will generate plenty of voltage at the lower speeds, but will reach it's limit above a certain frequency, and then drop rapidly.
In the middle-range, any scenario resulting in excess power will yield higher-than-proper voltage, wherein the rectifier-regulator will 'shunt' off excess power through it's resistor grid. It's like a crowbar circuit.
that means, if you're spinning along at 3400rpm, and the system consumption is very low, battery fully charged, that alternator is still cranking out 250W, and you're only using 65, the rest HAS to go somewhere.
It's a clever design in some respects... but in others... not so much.
They selected the permanent magnet system because it eliminated brushes and spinning field. This is one of the most substantial design improvements that an external alternator provides- when they regulate, the field suppression of the regulator REMOVES excess load, rather than dumping it to waste. More crankshaft HP.