Originally Posted by Looigi

For best LiIon life: Use until about 50% discharged and wait just before use to recharge. I approximate this as best as reasonable with my stuff and don't sweat it too much. e.g. My f/r blinkies have about 7 hrs of life. I might do two rides totaling ~4 hrs, then charge them up the morning of (or night before) the third ride. I usually don't charge the Garmin until it's about 1/2 down. Same with my phone.