Same as any other 12 volt battery. Test it with a DC voltmeter.
12.6 volts = 100% charged
12.4 volts = 75%
12.2 vlots = 50%
12.0 volts = 00%
This depends on the mower. With out knowing the make and model of the mower so I can look up the type of battery this question can not be answered
Dead cell in battery, loose of corroded battery connections, or the charging system on the mower engine is defective.
Do you mean that you can not charge it with a battery charger or the mower will not charge it while it is running? If you can not charge it with a battery charger and you are sure that the charger works then the battery is bad. These type batteries are only good for a couple years. If the mower is not charging the battery it could be a number of things.
they can be recharged by hooking jumper cables from a car to the mower or if the battery is fried you would have to buy a new battery for it Use a battery charger just like the one you use on an auto battery.
i dont see why not.
Mower has a generator, which is turned by the engine. When engine is running, generator produces electricity to charge the storage battery.
No, you can charge it on the mower and you do not have to remove it or disconnect the cables.
No, it is not necessary to remove it. You can charge it right there on the mower.
Magnetos
the magneto
probably
yes.