I had this same problem on a new hustler with a 25kaw, bought new battery, 3 weeks later,I'm jumpin it again. the dealer told me I wasnt running the engine at a high enough rpm to recharge the battery, it was during the drought last year and to save fuel and noise on thin grass I was running about 3/4 throttle, I still pull back on the throttle occasionally but not all day, the test we ran at the dealer was clamp meter to the battery and watch it as the engine is idling and at half and full throttle, even at 80% throttle the juice coming off the engine wasnt enough to recharge the battery, you may want to run this test on your machine, I am unsure of the specs but it is something like it needs 16 volts to recharge a 12 volt battery and at 75-80% throttle was only putting out 10.5 or 11 ,,, this situation will affect your machine more if you have a lot of small lawns,which would mean a lot of starts/discharging.. someone suggested I put a battery maintainer on the mower and plug it in every other night if I just cant stand to run full throttle all the time, I may do just that this year if we have another slow growth period as I hate to run wide open in small areas, sorry this went long