I've just seen, voltage set point 13.8v
That's too low for a modern battery?
Yes, 14.2 is more like it. However
A more powerful alternator that helps when you have heavy load items in use much of the time like winch doing a job like log hauling or playing in a winch challenge.
At other times in every day running say after starting up it just replaces the charge in the batt at a faster rate putting more load on the engine but for a shorter time.
It could be the lower voltage set point of 13.8 is done to protect the batt from negative effects of "fast charging"
I have an old fashion batt charger [no fancy regulator controls] with 3 settings, trickle for overnight charge 3/5 amp, Boost 20amp for when you need to get going in an hour or so from finding your batt is flat. 180amp start to get going quick. Once running disconnect or batt will be damaged.
So you can see it is important that the regulator on an alternator does its job. Even if an every day alternator go's duff while still working it can soon wreak a batt.
A friends car had done for 2 batts both fried. A test on his alternator showed it was putting out 22/23 volts and pushing however many amps into an already charged batt.
It is more usual for a regulator to just quit, a good thing I recon.