My bulbs (Philips 3 pack from H-Deezy) have a stated life of 3000 hours. The way I under stood it was life decreased logarithmically as you increased voltage linearly. So a 20% over volt (14.4V) would give a 5% bulb life.... so about 150 hours. However, you get 80% more light from the bulb. To me, that's a good trade off.