Small Aircraft; Low Wing; 1 Eng; Fixed Gear
Flight Crew Commercial; Flight Crew Flight Instructor
Flight Crew Last 90 Days 43.4; Flight Crew Total 480.5; Flight Crew Type 240.2
Situational Awareness; Training / Qualification
Ground Excursion Runway; Inflight Event / Encounter Loss Of Aircraft Control
General None Reported / Taken
Airport; Human Factors; Weather
I was on a training flight with my student and was coming in to land on runway 23L at BTL.  Runway conditions were some compacted snow and a little bit of ice; the ramps were all covered in snow.  Upon touchdown the airplane veered to the right; indicating that I had a locked brake; I also believe that I hit a patch of ice as I touched down.  I used left rudder to try and maintain lateral control to initiate a go-around.  Upon increasing power for the go-around the airplane veered more violently to the right causing us to veer off the right side of runway 23L.  There were no injuries; nor was there damage to the plane or the runway environment.
Flight instructor reported loss of directional control and a runway excursion after landing at BTL in snowy and icy conditions.