What is the tractor? The L2550 listed in your equipment? How many hours, and what's its maintenance history?
What did it do when it died? Smoke? If it smoked, what color?
Bog down for a while or just quit real quick?
My first thought is dynamo or alternator, but really just guessing. Not sure what an L2550 has in it. Might check to see if spin free, belt tight, wires connected, etc.
Make sure all battery connections clean and tight, both hot and ground and also at the battery and frame, etc..