This video describes how to remove and replace the batteries in an Acorn Superglide 120 Stair Lift. You will need a regular length and a short phillips head screwdriver, plus something to cut a large plastic zip tie. The video is mostly filmed in real time and it takes less than 10 minutes to remove the batteries and about the same to replace them. The average life span of this type of battery is only 34 years so this is something that is good to know how to do since it will need to be done regularly. If either one of the limiter switch plates happens to come loose while removing the cover don't worry they will snap right back on very easily. The batteries cost around $35 to $40 each and are readily available.