Do Lawn Mowers have alternators that charge their batteries back up, or
do they just die out like any other battery, then you have to replace
it?

The reason I'm asking is, my battery recently died on my Murray and I
charged it up. Worked like a charm. I mowed my entire yard, then
tried to get some tall grass in the back of the yard and it killed my
mower. When I tried to restart it I had no luck. It acted like it did
the day before when the battery was dead. I haven't recharged it yet,
but I'm pretty sure that's the problem.

Any suggestions? New battery time or could it be something else.