L3901 Battery keeps dying

[RGAZ]

I would pull the alternator and have it tested. Its possible there is a bad diode or something in the voltage control that is not providing full amps at full engine speed. I have seen auto alternators that will show charging the battery and the battery shows a float voltage, but when actual current is drawn, the alternator falls on its face and the battery does all the work. In some cases the alt light will dimly flicker or slightly turn on, but not always.

If you don't want to bother, then I will concur to just replace the battery.

Good luck,
RGAZ

 

[Fallon]

Check the ground cables. When my L3200 was only a couple years old I had ground issues. Spent hours with a multimeter & wired readings. Ground was clean & tight. The second I started loosening a ground bolt up the hazard lights started clicking away & I realized I wasted hours. Others said ground issues, but it looked good so I didn't mess with it.

 

[Fuddy1952]

as my post indicates, I have already used a multimeter and also there were no warning lights on panel.

As other's said you get more help answering questions. You said you used a multimeter but didn't list results. "After mowing for a couple hours, it won't restart (standard dead/low battery noises when key is turned) and has to be jumped. Last week, it even died while using it"
The battery and alternator is basically all there is, other than of course wiring problem.
A meter used properly will tell a lot, but what is the battery voltage? Voltage while cranking? Voltage running? Voltage running with lights on? Etc.
As other's said, a battery can have strange problems. Maybe you could simply swap that battery for another known good one, out of another vehicle. Easy free test.

 

[5030]

I would pull the alternator and have it tested. Its possible there is a bad diode or something in the voltage control that is not providing full amps at full engine speed. I have seen auto alternators that will show charging the battery and the battery shows a float voltage, but when actual current is drawn, the alternator falls on its face and the battery does all the work. In some cases the alt light will dimly flicker or slightly turn on, but not always.

If you don't want to bother, then I will concur to just replace the battery.

Good luck,
RGAZ

feel the alternator with the engine running (for a while), if it's warm, it's working fine. If it's cold, it's shot. Real simple, no meter needed.