Yesterday I did a charge/discharge/test of 1 cell from each of the 2 Roomba batteries using the Lacrosse charger. Apparently using the charger on the larger capacity batteries works, but there would be no thermal detection, so the charge process relies on change in voltage detection only.
The Lacrosse showed 1 cell having only ~200mA, and another cell having ~2100mA (out of 3000 rated).
I'm now testing 4 cells at a time, all from different battery packs; 2 Roomba, and 2 Neato.
If I determine that 3 or less cells need replacement, I'll revive the pack by replacing the failed cells.
Here is my actual setup, showing the stripped down Lacrosse charger and various batteries. As I left for work today, I connected 4 batteries and set them at a charge rate of 1000mA, or 1/3 C.
Part of the reason I want to become familiar with battery maintenance and repair is that I plan to buy a used Prius and want to know what to do to keep it going. I might even buy one with a bad traction battery, or one with a branded title to save money. Plus, all of this is fun!