I have a 2020 utility tractor with a gas engine. I use it maybe once a week around the farm. It consistently refuses to crank. Why? because the battery is always dead. Put in a hot battery and it will crank instantly. Let it run 10 minutes or 5 hours and turn off the key. Turn it back on and it will drag as if the battery is dead. Maybe turn over once or twice real slow and then start clicking. Jumper cables or battery booster changes nothing. You can recharge the battery but after a few more times of draining, it won't hold a charge any longer. I had the starter checked and the guy said it was ok. I put a negative ground disconnect on it because I thought while it was sitting idle that it had a short draining the battery. Didn't help or change anything. Alternator is working fine also. So what is killing the battery? This has been going on for about a year now. Very frustrating and getting expensive. Opinions wanted please.