Surging lights

Firstly you should never undo the battery terminal with the engine running, the voltage spike created when touching it back on can do serious damage to the ECU, now, I would be getting the alternator checked as this may be a faulty voltage regulator, the surge in the lights may well be the voltage increasing and decreasing due to a faulty reg, start here.

Mark (mhpautos)

Also a dimmer and headlight switch -as advised with the voltage regulator can be integral with the alternator or the alternator's field generation of the alternator is being controlled by the computer