The chair is running a motor, an inductive load. They really aren't meant to run that type of load, because of the quick drain much like a laser printer. I don't know of too many other economic choices. You need power when commercial power is out. I would test it before you need it and occasionally after it is installed to make sure it will work and not overload the circuit breaker. Remember the lead acid batteries last about the same as car batteries. They need to be replaced some time in the future and that may be as little as every two years.