Why won't my new battery stay charged o my murray riding mower

Most mowers don't have a charger (duel magneto) onboard.

Contrary to what the other poster claimed... all electric start riding mowers have a charging circuit built into them to charge the battery... if its discharging you might have a load draining it when you think its switched off. Since it's a new mower it will be under warranty... I'd take it back for warranty repairs.

Contrary to what the other poster claimed....all electric start riding mowers have a charging circuit built into them to charge the battery...if its discharging you might have a load draining it when you think its switched off. Since its a new mower it will be under warranty...I'd take it back for warranty repairs.

Manufactures seem to have an open window for dishonesty and most buy into the notion that businesses are honest. Businesses are in business to make money this is their only simple function. Take the top cover off your motor and chances are it is a single pole magneto one big magnet with three wires extending from it one of those with a 0.37 cent chinese diode attached for the charging circuit. A 12 volt battery will need a minimum 12.7 volts for one hour to recharge just from starting if it is a long crank time more time will be needed for charging. Duel magnetos exist as far as I know, only on Snappers the rest have this crappy electronic three wire BS. If it is under warranty do take it back but know that it will not keep your battery charged. A battery tender can be bought on Amazon for a reasonable price.

(Note: OP doesn't say that it's a new mower, only says it's a new battery.)

Manufactures seem to have an open window for dishonesty and most buy into the notion that businesses are honest. Businesses are in business to make money this is their only simple function. Take the top cover off your motor and chances are it is a single pole magneto one big magnet with three wires extending from it one of those with a 0.37 cent chinese diode attached for the charging circuit. A 12 volt battery will need a minimum 12.7 volts for one hour to recharge just from starting if it is a long crank time more time will be needed for charging. Duel magnetos exist as far as I know, only on Snappers the rest have this crappy electronic three wire BS. If it is under warranty do take it back but know that it will not keep your battery charged. A battery tender can be bought on amazon for a reasonable price.
If its got a starter.. and it's a riding lawnmower.. then there is ZERO possibility it doesn't have a charging circuit.

Snapper mowers don't have engines that are any different than used by other manufacturers... they buy their engines from the engine manufacturers just like every other lawnmower manufacturer does.

And I do personally know Snapper mowers very well. I even have one that's over 30 years old... its a surprisingly rugged little rider given its simplicity and diminutive size. I have a variety of mowers in fact. Both riding and push mowers.

What someone's impression of honesty in manufacturers has to do with this is beyond comprehension... Being this one name was brandished around... Snapper has been in business building their riding mower without huge changes sine the mid 1950's. If it wasn't a good product... they would have a bad reputation and they would have been run out of business... the fact they haven't in nearly 60 years speaks volumes.

A batter tender is great to use during the off season but it doesn't charge a battery that's discharged due to a defect in the charging system. It keeps it at the optimum charge.

To the OP... if you can be more specific with the brand and model your mower is... we can provide more specific advice.