The burn time is significantly less than three hours. Since I have not used continuously, I can only guess that, so to speak. Overall, it could be more. Charging via USB is yes for a relatively convenient and can happen on the PC, but this is - unlike the good old battery - right on traveling and outdoor without a laptop rather unfavorable. We noticed this summer while camping. If you had not somehow happens to have a power source, together with computer or charger cable to hand it looks rather bad. So rather a lamp for urban use, rather large for adventure in the Widlnis. Who so scrutinized something is very well served with this model.
