You need to buy a 112#. I have a 112# 36v freshwater Ulterra for sale for $1700. I'm outting on a saltwater Ulterra. Look at the Minn Kota precision chargers.
Capt. Craig Copeland
2013 Nautic Star 2110 Shallow Bay Boat
Humminbird HELIX 12 CHIRP MEGA SI GPS G2N
Nautic Star Boats Pro Staff (nauticstarboats.com)
Redneck Fish'n Jigs Pro Staff (redneckfishn.com)