4020 w/ 24v system sparks when the battery is connected

needs battery and or cables. check connections for corrosion. use ohm meter to check voltage on battery.

I’m happy to assist further over the phone at https://www.6ya.com/expert/howard_977676954994c5b2

Battery is low. Either the battery is bad or the charging system is bad. You should read 12.5 volts or more when not running, 14 volts when running.

Sparking between the lead and positive terminal when connecting them is normal. But you should always connect the positive first then the negative.

Only option left.... 12 volts feeding coil is not there. The ignition key applys the 12 volts to the coil in the "Run" and "Start" positions. Verify 12 volts at input to coil and then (if needed) follow wire back to key and confirm voltage there....and (if needed) follow input wire to key from battery. One of those critters is open - since you have already confirmed the coil/spark plug wire is not at fault.

Yes, you can jump start it with any 12 volt battery on any vehicle. Just do not have the donor vehicle running. Connect the positive cable from the donor battery to the positive post on the battery on the mower. Then connect the negative cable from the donor battery to the engine block or other ground source on the mower. Do not connect it to the negative post on the battery. Make sure you have a good connection on bare metal for the negative cable. Disconnect the negative cable the instant the mower starts.

check the battery with a multimeter and see if its showing 12 volts or more, if its not showing any volts the connectors on the battery under the plastic housing have probably come disconnected, you'll then have to pry off one side of the battery and reconnect them, if it is showing volts but not 12 or more then put it on the charger for about 8 hours, then check the battery again if it still hasn't went up check the voltage of the charger with the multimeter and make sure that the charger is putting out 13.8 volts or more, iif it isn't then you need a new charger, if it is then you need a new battery

The 3010 24v JD system is not a true 24v system. It is a balanced split 12v system, with one positive ground battery and one negative ground battery. The only 24 volt accessory is the starter, where the batteries meet in a series to provide 24 volts for starting. All other accessories are 12v, half powered by the positive ground battery and half powered by the negative battery. The generator charges one battery in one direction and the other battery in the reverse direction. Therefore a 24v alternator is not easily adapted to this system.
The usual solution is to change to a 12v system with an alternator, changing the starter to 12v and changing the polarity of the positive ground battery to negative ground.
The cost of a 12v starter and alternator is far less than the cost of a 24v alternator, plus the added benefit of using 12v lights and other accessories.
JD switched to this 12v type of system with alternator during the 20 series production, but used two 6v batteries in a series due to the larger cranking amp rating of the 6v batteries occupying the same physical space.

nope it will fry out the motors, you can order an oem 12v battery here www.powerwheelsoutlet.com

They came out with 24