The subject of the upgrade is a handheld vacuum. Specifically a Black & Decker BDH9600CHV, a member of the "Dustbuster" line whose success defined a whole new product category.
A major factor of the success is their easy of use. Whenever there's a cleanup task, it's easy to pull the vacuum off its charging stand and clean up the mess. No need to pull a big heavy vacuum out of the closet, no need to look for the nearest plug. A small cordless handheld vacuum is very convenient and people are willing to pay for that convenience.
The basic design of a Dustbuster is straightforward: a battery pack hooked up to a motor controlled by a switch. As a result, the majority of the vacuum are durable and reliable thanks to their simplicity. With the notable exception of the battery pack. The battery pack is what makes the cordless vacuum possible and easy to use, but the battery is also the weakest link.
This particular Dustbuster had been sitting in the standby charging base and the battery power capacity gradually dwindled over the past few years. Now the battery pack, even when freshly charged off its charging stand, could only offer a little bit of power before the motor slowed down and couldn't generate enough vacuum to be useful.
In today's disposable society, it's easy to just throw away such a simple and inexpensive appliance and buy a new one. But where's the fun in that? Since the rest of the vacuum seems to be OK, the goal of the new project is to give this vacuum new life by some combination of repairing, restoring, and/or revamping the battery pack.
Let's open it up and see what we find...
(Cross-posted to NewScrewdriver.com)