Invacare m51 scooter. I just replaced the batteries in my dads chair. We charged it all night the first night and it ran great the next day. recharged it for several days after using it and now the battery is running down within an hour. (The controller has several lights and it looses 3-4 of the green lights within the hour) When we charge it the red light is lit as well as the green light.

Sweet you do not need to leave the charger plugged in for several days. Sounds like there is a charger problem When you first plug the charger in with batteries depleted you should be getting a red and yellow light with the yellow turning green when fully charged. now the charger (built in) could have become unplugged from the power module located in the rear of the chair behind the black cover. To get to it you have to remove the seat, shroud and batteries then using a phillips screwdriver and adjustable wrench remove the black cover. The charger cord will be the last one on the left with a small 4 pin white plastic plug make sure it is well seated in the power module. If it isn't loose then you have a problem with the charger or the circuit. Now if you know of a friend that has an off board charger for a chair or scooter that you can borrow you can charge the batteries using the charger port located under the front of the joystick Plug the charger into the port then into the wall socket and let er rip Charge until the light turns green overnite is a good habit to get into If the onboard charger is bad I would suggest you by an offboard charger (cheaper) Now if Medicare paid for your Dads Chair then they will pay for any repairs even batteries and you can contact the provider that your dad got the chair from to see if they will repair it Hope this helps