1 red light blinking on the joystick means the batteries have a low voltage probably under 9 volts and will need to replace the batteries. If its a Jazzy Elite it takes 2 -12 volts 35 ah batteries. (U1) . The jazzy battery charger has a 3 step charging system the first light is solid red when charging the unit after a few hours the red light will blink going into a rapid charge once the light turns green the system is fully charged. if the person that is using the unit is an active user I would recommend to charge the unit every night 10-12 hours. Hope this helps...