Does the stator put out a set amount of power when charging the battery or does it adjust as needed?

I ask because my headlight stopped turning on after I started my bike. I think its the junction box where the headlight relay lives but I haven't tested it/am not great with electrical troubleshooting. I bypassed the junction box completely and ran a wire from the battery, to a new flip switch, to the high/low beam switch to get me back home (finishing a cross country roadtrip) -- after about 30 minutes of riding the bike started to die until I turned the headlight switch off.

The only other thing I can think is the issue would be the stator is failing causing the relay to not close and the headlight to not go on -- It would also make sense since the bike couldn't maintain the battery while riding with that headlight on.