A number of reviews indicate that the battery backup system does not work. I feel that these comments my be misleading to someone reading the reviews and that the writers may think that the chair can operate on these 2 9V batteries.   In the manual it says...

2-9 Volt back-up batteries will operate the chair from the reclined position to the seating position. The batteries will operate one cycle in case of a power failure. Replace the batteries once per year or if used during a power failure.