The numbers were idle but I don't think it makes that much difference.Is that just at tick over ? Does it get better at say 1k5 rpm?
I don’t think it unreasonable to expect a modern alternator and regulator to hold nearer the 14.2v with a 40a load.
Same timeline and added the current (this is the current into the Leisure Battery, so the B2B is pulling more (charger inefficiences plus around 1A the system is using) and there is the 12V into the Fridge as well. But the Current is fairly constant and the voltage varies by maybe around 0.1V and each of the 3 seperate driving sessions are pretty well the same (with Lights on - so an extra 10A load or so - on the 2nd and 3rd sessions).
I don't think Alternators fitted to vans as standard are as high & precision bits of kit people think they are!