I don't know if this is an option you'd consider, but perhaps rebuilding that 170's battery is worth thinking about. Unlike batteries based on, say, lithium, the NiCds in that pack don't require particularly delicate handling. They're just cells assembled in a simple configuration. No "smart" circuitry; just a thermal fuse. That's it. So if you can find a source of decent NiCd cells, you can rebuild these packs very easily (more so if the cells come with tabs already spot-welded on). Long ago, I got a great deal on cells, and set about rebuilding many packs for myself and friends. They (packs and friends) lasted a good long time.