movements and included two compartments, one used for the battery
packs and the other for the computer and filter controller. The
original design criteria stipulated that the batteries had to support
2 hours of continuous use. This criterion can be met using 3–5 A h
battery packs. With battery weight no longer a limiting factor,
10 A h battery packs were used instead.
The choice to use a backpack also influenced the selection of the
laptop. The original laptop was replaced with the Dell laptop because
the Dell laptop has an external power button and all connections
are across the spine of the computer. The original laptop had
connections along both sides of the computer and accessing the
power switch required removing the laptop from the holder in
the backpack and then opening the laptop