I can't say for sure: on my model (approx. 1 year old), the green LED lights up when charging and always stays on, whether the battery is full or not. I simply leave the OneBlade on the charger for a few hours. On the other hand, the runtime is clearly better, definitely a couple of hours with apparently full power. I would think your battery is at the end of its life. Replacing the battery would be ideal, but I'm afraid green is just the colour of the handle...