Stair Lift Types
There isn't a lot of difference in stair lifts when it comes right down to it. All stair lifts work basically the same way but some designs are better suited to certain applications than others.
Power Supply Type
Battery power is the most common form of powering stair lifts today. The battery is located under the seat of the stair lift and will power the stair lift up and down the stairway several times on a charge depending on the age of the lift battery, the condition of the lift and the size of the user. The stair lift battery will automatically recharge when the lift is not in use and "parked" at the end of the run. When parked, an electrical connection is automatically made with charging terminals on the track.
The advantages of the battery powered stair lift is that it will still work in the event of a power outage and there are no power cables attached to the chair while it is being used. These power cables, know as travelling cables, are often the cause of break downs and malfunctions as the movement of the chair will over time cause the wires inside the cable to break.
House Current Powered
Stair lifts that operate on standard house current are usually older models. They are generally a bit more powerful than the battery operated units but will not work during a power failure. They require dedicated circuit from the breaker panel and will draw a large amount of power during use. Additionally, the travelling cable mentioned above is normally under constant tension that over time, when coupled with it's continual flexing while the chair is moving, will wear out.
Thirty years ago before batteries and technology improved the house current powered stair lifts were the only option. While they are older technology, these stair were capable of many years of trouble free service without any major problems. The biggest advantage they had over the battery powered models is that there are no batteries to replace every few years.
Outdoor Stair Lifts
Although the vast majority of stair lifts are designed for indoor use there are a few that are designed for outdoor use. They are usually the exact same as units used indoors but are weatherproofed as much as possible to prevent rain and snow from damaging the components of the stair lift. Even though the outdoor stair lift is built to be water resistant they will usually come with a tarp or cover of some sort to provide additional protection when not in use.