I haven't tested it yet, but the 1156 bulb I used shortened run time by about 40 minutes. Since my commute is about an hour and I recharge at work, I was never in danger of running out of power. But if I wanted to run 40W in the front, I had to cut back in the rear. Still, replacing the 1156 with the LED beehive 8-LED truck marker actually increased brightness.