Hydrogen RC car

I car works perfectly fine with the hydrogen fuel but the only problem is it that it dies really quickly. I timed how long the car would keep racing and it wasn't that long. So i try to find out the problem and why the battery dies so quickly. The battery is fully charge so i don't know why it's dying quickly. For now i'm working on the second hydrogen car to see if it will race better or the motor is the real issue in the RC.