No, I did a run time test the first time I bought a decent LED light and got 3 hours on high. Since then I just charge every few days, I don't keep track of anything. This time of year I'm on high if it's dark, low if it's dawn, strobe if it's daylight, so probably on average 50% utilization so I should expect 6 hours on a charge. I ride about 80 minutes a day and I try to remember to charge after 4 days. Since I don't really keep track very well, I also have a lockblock on my bar and toss a flashlight on if I lose charge in the middle of a ride (I would carry the flashlight/lockblock backup even if I had a dyno - I do not trust any system that much). I rarely have to do that. So at a guess I'm still getting close to the original run time on the batteries.

Since I carry a backup for both front and rear lights anyway, I am very laid back about charging and don't really worry about it at all. If I go out in the morning and a light is dead I swap batteries then - when it's charge time I just swap the battery on the bike with the one on the charger.