I do that, too, but wonder if it's better to bring the charger to work and charge it right before using the light. If it's charged to full compacity on weekend, it will be on full charge for the duration between weekend and the time it gets used (say Monday night). I thought keeping the battery on full charge is not good?
Keeping the battery at full charge is less than optimum but sometimes it's not practical to charge right before riding. With LiIon batteries, the longest useful life in terms of total run time before needing replacement will be if you charge the battery just before use and discharge it to ~50% of capacity before recharging. I try to approximate this as best as practical with my devices.