Park the Cub Cadet on a flat surface with no inclines and engage the safety brake.
Raise the engine cover on the Cub Cadet.
Turn the multimeter on and set it to the voltage setting. Place the meter's negative lead to the battery's negative terminal and place the positive test lead to the battery's positive terminal. The reading should be 12 volts. If it falls below this, attempt charging the battery first.
Use a wrench to remove first the negative and then the positive battery cables from the Cub Cadet's battery terminals. Hook up the battery charger to the battery. Place the charger's negative clamp on the negative battery terminal and the positive to the positive and then plug the charger in. Allow the charger to charge for at least six hours. Try to start the tractor after this time has elapsed. If the tractor will not start move on to the next step.
Grab the old battery and lift it out. Set the new battery in and replace the cables, tightening them down tight with the wrench. Test the new battery by starting the tractor.