9 LEDs / 3 rows means Fully Charged, 6 LEDs / 2 rows means 60 % Charged, 3 LEDs / 1 row means 30 % Charged. No LEDs means that you need to charge the NeuroVizr(TM) for 2 hours My NeuroVizr device do not charge anymore. The NeuroVizr is rated for continuous operation. The device can be used while charging. Charge time from empty to full is 2 hours. The NeuroVizr can be taken on a plane, either in carryon or checked luggage. Do not attempt to change the Li-ion rechargeable batteries. Doing this may result in a hazard. Typical Li-ion battery life is 600+ cycles. Battery pack replacements are available. Please contact our customer service at customer@neurovizr.com