A red light on your Bitvae electric toothbrush could be one of the following things: - Some of our toothbrushes feature a visible pressure sensor. If you're pressing too hard on your teeth, it will light up. This light helps you remember there's no need to brush hard, rather move the toothbrush slowly from tooth to tooth and let the brush do the work. - If the red light is near the bottom of the handle, this could be the low battery indicator. It lights up when it’s time to charge your toothbrush, as there is only enough power left in the battery for 1 or 2 more brushes.  - Lastly, when plugged in and charging, the red light above the charge indicator will illuminate. When it's done charging, it will turn off.