Most likely your charge isn't charging properly. You need a multimeter to test the voltage at the joystick. In the 3-pin femal connector measure the voltage across the two horizontal terminals. It should read about 24 volts. Now plug it into the charger and see if the voltage increases, if not, charger needs to be replaced. You can get one that plugs into the joystick on ebay a lot cheaper than going to the mfgr. about $50.00 or so. Even if the lights are blinking, it may not be putting out sufficient voltage to bring the batteries up.