The Nite Hawk charger is actually pretty simple as chargers go; it's just a two-stage charger. If the battery voltage starts below a given threshold, it runs in "high charge" mode; it maintains this until the battery reaches a threshold, at which point it switches to a simple float charge. The float charge mode maintains constant voltage. (The op-amp on the left determines which mode it's in; the one on the right just acts as an inverter.) They've got that 7812 voltage regulator (U2) hooked up in a weird sort of way, though.

The only way I could see to simplify it more would be to either make it a fixed-voltage float charger -- which would take a long time to charge, and may not use the battery to its full potential -- or by making it a trickle charger which must be removed after a certain number of hours. They've got a nice mix here: it charges up most of the way in <8 hours or so, but then switches to a float charge that can be maintained indefinitely. "Fire and forget."


My Nite Hawk ("Dual Pro") has no control box; the control system consists simply of plain-jane switches, with weatherproof rubber boots over them.


Out of curiosity, where did you tie into the system, and how much current does your brake system pull?

If they've got some fancy digital brightness control, it could be running at high frequencies, and it might be sensitive to additional load... particularly reactive loads.