SmartHalo charges best when plugged into a computer USB port.
When you plug SmartHalo in, you should see the centre light flash green. Then you'll see an indication of how much your SmartHalo is charged by a circle that fills from red-to-green. One red dot indicates that the battery is at 0% and a full red-to-green circle indicates that the battery is at 100%. Touching SmartHalo's surface while it's charging will show the charge level. You'll also see the charge level when you unplug SmartHalo.
If you're charging SmartHalo through a wall charger and you're not seeing the green centre light upon plugging it in and the red-to-green circle indicating the charge level, please plug SmartHalo into a computer's USB port.
If SmartHalo reaches 0% charge, it may take a few hours to see progress in the charging.