blades diaengage and battery dies

Hello, I have a craftman 46 inch pro series riding lawn mower. It wouldn't start even after charging battery. Changed battery, cut 1 acre just fine, midway through the next cut the blades would disengage, engine would rev a little faster and the steering would get tough. Turned mower off and wouldn't start back. Put on charge for about 30 mins, mower started back up, ran for about 10 mins and I repeated the same process 2 or 3 more times until I finished cutting the yard. Any thoughts?