Tony welcome to WFM. It is not unusual for the small garden tractor batteries to die every couple of years. When I worked for JD in the 1970s the RF batteries only had a 90 day replacement warranty. Here are a couple of tests. With the ground cable removed from the battery and the switch in the off position touch a test light to the negative post on the battery and to the ground cable or just to the frame. The light should not light up. If it does you have something that is staying on with the switch off that will drain the battery. Lots of possibilities for that including a bad voltage regulator or a shorted wire. A second test with the battery all hooked and the switch and engine off test how many volts the battery has. It should be close to 12.5 volts but 12 volts is acceptable most of the time. Now start the engine and with the engine at 1/2 throttle or above test between the battery posts again. You should now get a reading of 13.5 to 14 volts. If it stays same as the first reading either generator or voltage regulator is bad. I have one more test but try those first. Roger