used roomba battery

I have a “dead” roomba battery pack. After disassemble, I found 12 NIMH batteries in them, the form factor is like a C cell, but smaller in diameter and also length. They seem to all hold a charge, so I suspect the on board circuitry was bad. What can I do with these odd ball batteries?

Those are sub-C batteries. Official dimensions: diam.22.2*42.9mm.

I have 8 of those out of RC packs where one cell died and croaked the pack. I put a small washer on top, then a strong magnet about the size of a very thick button. That keeps the washer stuck mostly in place. This allows it to work in applications that are not diameter dependent. I have a couple LED ceiling lights that can use 4xC that are hell on batteries so I need to swap them out ever 1-2 weeks.

If you have an analyzing charger you might want to cycle them and check the capacity first to see if they are worth bothering with.