Small Engines (Lawn Mowers, etc.): MTD yard machine going through many batteries too quickly??, briggs and stratton, spec numbers

Question
I have an MTD Yard Machine Lawn Tractor model (13AS695H372) with a Briggs and Stratton I/C 18.5 TwinII engine -- Model (42A707) Type (2238-E1) Code (9803185A).  My problem is that the tractor is going through batteries very quickly, that is, I cannot get a battery to last more than 5 to 10 starts before it will no longer turn the engine over with enough force to start the Mower.  If I jumpstart the mower from my car or buy a new battery the mower starts right up and runs very well, but as time goes on the battery does not seem to be getting recharged when the engine is running.  Why would I be going through batteries so quickly?  Is the battery not charging when the engine is running? Could it be the starter? Not sure what part to order to fix it?  Can you help.

Thanks in advance,
Tony

Answer
there  at times is a charging system  fuse which may have bown out.  you have to check  for it behind dash area,  by  stater area???  or where wires from engine come out from engine area.if you have a charging gage in dash   it should show charging by being abit over center with needle reading twards postive side. you may  while running put a gage on  battery to check if its charging.  if none of this you find is not working, the charging coils under flywheel may have crapped out. that whould need to bereplaced and ordered from your dealer >> via   spec numbers.