How long does it take to charge my MJ401C-XR lawn mower? & how long will it last? It will take, on average, 5 hours To fully charge your MJ401C-XR lawn mower depending on the remaining charge of the battery. A fully charged battery will give you a total of 30 minutes of cutting time. Related articles Can you remove the batteries from this unit? How do I adjust the cutting height on my Sun Joe Mow Joe MJ401C-XR Lawn Mower? How do I know if the mower blade on my MJ401C-XR needs to be replaced? Battery and Unit Compatibility Guide General Troubleshooting for Battery and Charger