24/7 Notebook Power?

RobPiano asks: "Help! I am working at a health care facility that may be expanding its network to have eight Fujitsu wireless notebooks. These notebooks would be required to run nearly 24/7 with minimum downtime. Unfortunately, charging and replacing lithium-ion batteries is expensive, and cost is definitely an issue. The notebooks are placed on carts, so an 'on-cart power supply' is an option, but having it plugged in is not. I considered a car battery, but most of the nurses would have trouble pushing both cart and battery. How have you readers kept your systems powered?"