Check Charging System?

I recently installed some halo headlights into my 2010 mustang. I read a few forums before purchasing them, and noticed a couple of people said that the check charging system light came on and that you were supposed to unplug the negative on the battery before installation. I installed the lights fine, but now the check charging system light is coming on. My battery is putting out about 13.5 volts and around 80 amps at idle... If anyone knows what the heck is going on, please help!!