All our rechargeable products use lithium batteries, including (Q3r, Q4xr and Q7xr) which comes with a spare lithium battery as a standard, and have as a safety measure only batteries charged to 30% while being transported. If you only use one of the batteries, or if the spare/secondary battery is not used for a prolonged period it will discharge completely.
Reguarly check your batteries
The state of charge level should be checked regularly (every 3 months) and provision should be made for recharging the cells, before the cell voltage drops below the recommended minimum after which the cells suffer irreparable deterioration.