A&C
Not a cover up. Piper apparently delivered the aircraft to the first owner in Canada with this option fitted and it was reflected in the POH.
I can't remember the exact details, but IIRC, the battery was considerably heavier duty than the normal unit.
BTW, I didn't fly the Arrow below the POH v speeds, I trimmed it a little tail heavy to make holding off a little easier - sorry if this wasn not clear. This meant holding a little forward pressure on short final.