I have several Spinners, and none need to be turned off to charge.
In my experience, if the battery light stays on, it indicates a deeper state of discharge. A full charge can take about 4 hours from that point of discharge, and part way through the battery light will go off, charger light still red. Near full charge, the charger light will start a slow red/green blink.
If when you start the charge the charger light stays green, it's indicating a poor connection to the battery. Clean all contacts and try again. Even with a fully charged battery, the charger should go briefly red as it tests the battery voltage.
In my experience, if the battery light stays on, it indicates a deeper state of discharge. A full charge can take about 4 hours from that point of discharge, and part way through the battery light will go off, charger light still red. Near full charge, the charger light will start a slow red/green blink.
If when you start the charge the charger light stays green, it's indicating a poor connection to the battery. Clean all contacts and try again. Even with a fully charged battery, the charger should go briefly red as it tests the battery voltage.