Greetings, I don't know anything about the
l245dt, specifically whether it has a separate regulator or if it's built in to the alternator/dynamo but most all charging systems work using the same in basic principles.
Have you read the voltage across the battery with a volt/ohm meter with the engine off and then compared it to the reading when the engines running?
With a good battery, you should see around 12 to 12.5 VDC with the engine off and from 12.8 to 14.5 with the engine running. It should always read higher w/the engine running.
If it reads the same or lower than your charging system isn't working.
Check for blown fuses, loose alt belt and make sure all the elec., connetions are clean & tight. A loose battery terminal may start the engine but vibration from the running engine can keep it from making connection for chargeing.
Also, it could be that the winch you are using is pulling more current than your alt/reg can produce. If this is the case then the battery will discharge every time you use it.
Most tractor's charging systems produce around 15 to 20 amps @12VDC. You may check to see what your tractor's output specs are and also what the winch draws.
Sometimes you can get a high output alternator kit too.
Good luck
Volfandt