It sounds like your OcuMow16MX is performing correctly in terms of run-time, but there is a bit of a misunderstanding regarding how this specific model recharges.

The OcuMow16MX is designed as a manual-charge model, which means it does not have a charging station that it automatically returns to when the battery is low. When you see the "low battery" message, the mower will simply stop where it is.

To charge the unit and verify that it is receiving power, please follow these steps:

Remove the Battery: You will need to manually remove the battery pack from the mower’s battery compartment.
Use the External Charger: Plug the battery into the separate charging unit that was supplied in the box with your mower.
Check the Indicators: To tell if it is actually charging, look at the LED indicator light on the charging brick itself. Usually, a solid red light indicates that the battery is currently charging, and it will switch to a solid green light once the battery is at 100% capacity.
Because this model doesn't "dock" itself, it won't charge simply by being parked in a specific spot or left on the lawn. Once the battery is fully charged (green light), simply slot it back into the mower, and you’ll be ready for your next session!

I hope this clears things up and helps you get back to a perfectly mown lawn.