Spartan HUD – Next Generation Augmented Reality Helmet

Good question. Well first before that happens, you'll get warnings at approximately T-3 hours, 1 hour left, 30 mins left, 10 mins left.

From there you just need to find a wall outlet and use the included charger. Typical use will have you good to go for an 8 hours of continuous high energy use (up to 12 on lower intensity activities).