Someone gave me a pronto m51 sure step motorized wheelchair but no manual was given..my question is: Is it safe to charge the battery overnight? Is there any danger of overcharging? If anyone knows for sure please let me know..thanks jo

Jo, nope you are safe. Most of the chargers are designed to cut off and go into trickle charge once they sense that the batteries are fully charged. The problem with overcharging comes after 18 hours or so. You should never leave the charger plugged into the chair for more than 24 hours. On the M51 the charger is built into the chair so just plug it in when you go to bed and unplug it when you get up and you'll be ok. You can check for full charge by looking at the charger there should be a red light and a green light when fully charged. Hope this helps