My Craftsman II hp yard tractor will not keep the battery charged. Model 502254262, any ideas on what the problem is?

Two things, it could be the battery itself can't hold a charge or the engine is no longer generating 13 volts. If you have sensitive enough testers you can measure what is charging back to the battery when the engine is running, should be 13 volts. Also just try swapping the tractor battery with a car battery or another tractor or motor cycle battery to see if it's a bad battery