Outdoor Power Equipment and Small Engines - Tractor batteries keep dying

I'm on my third battery in six months on my lawn tractor. They last a month or so, then require a charge to start the motor and work for a couple of weeks, then die completely. Is this likely to be a problem with the mower electrical, or defective batteries? Does it make sense that my automatic charger registers a fault (according to the manual, this means the battery is too low to charge)?

We need more information. Such as tractor make and model, engine make, model, serial, etc., battery ignition or magneto ignition, and, manual clutch or electric clutch.

Murray Model 425001x8E, manual clutch, battery ignition I think.

B&S engine 17.5 HP Model 31C707 Type 0154E1 Code 041124ZD

You have an electrical power draw of some sort. There is almost no way you could get that many bad batteries in a row. If you can not find the power draw, there may be problems with the charging circuit. If the problem can not be found, I suggest you replace one of the battery nuts with a wingnut which will allow you to disconnect the battery lead easily. Disconnect after you use the tractor. See if that extends battery life.

If your battery charger indicates a problem, disconnect the battery from the wiring and try again. If everything shows normal at that point your problem is the wiring in the tractor. The fault indication may be your tractor wiring showing a short, which the charger can't distinguish from a shorted plate in the battery.