As it's a dynamo, probably not, but the crude alternator type systems generally have a winding for charging the battery, and another for directly feeding the headlight.
Have you replaced the headlamp bulb?, and how legal is it? - as far as I'm aware after market LED conversion bulbs aren't legal, as they don't match the headlight design.
But if you've gone to LED's you've drastically reduced your power requirements, and I would imagine the dynamo should be well up to the task now - it might be worth trying to make an electronic control unit, which should keep things more accurate.