Tried to jumpstart 12volt lawnmower battery

The charging system is good from the mower moter

Took battery in for the winter.so not half to do it

Battery will keeep a charge for the day.. you can turn it of and on .all day but it will go dead
Over night.. can any one help pleas .thank you

Try charging the battery with an ampere damper, so it doesn't charge above 2 amps--anything higher will damage the battery. If it doesn't hold a charge after that, something is wrong with the battery. A regular 6 amp charger will fry those batteries.