Hi Nick,
A few things that you need to know about the charging systems on these machines;
The charging system output comes thru the fuse with the yellow wiring.
From the fuse it goes to a terminal on the key switch.
In a normally functioning key switch, the charging system circuit is open when the key switch is in the off position. This isolates the charging system electrically when the engine is not running. The reason for this is with this type of charging system, which is very basic, if not isolated, power from the battery will backfeed thru the regulator/rectifier and into the stator which is under the engine flywheel and attempt to motorize which in a fairly short time will kill the battery.
I suggest after your next mowing that you remove the fuse in the yellow wired fuse holder. Leave the machine sit overnight, reinstall the fuse, and attempt to start the engine. If the engine starts without jumping the battery, then you have a problem with either the key switch or something connected around the key switch area.
With the engine running, check the voltage across the battery terminals with a voltmeter in the DC volts position and let us know what the voltage is. With a fully charged battery the voltage should be 13.9-14.3 VDC with the engine at half throttle or higher, mower deck not engaged. Check the fuse to see if it is blown. Never run the engine without a good fuse in this fuse holder as the regulator/rectifier will burn out.
Mad Mackie in CT
