Yes, those older Nickel Cadmium batteries are rebuildable and can be retrofitted with new 18650 cells. There's a bit of fiddling to get things to go back into place, but in most cases they can be done. The capacity is increased from 1.5Ah to 3.5Ah sometimes more. The voltage is the same, the Amp hours of the 'new' battery increases extending the run time. If you have a favourite power tool, where the battery has died long ago, ask for a quote. I have been wondering how many really nice Japanese and German tools ended up in landfill because the batteries are no longer manufactured? Hit up 'Darth Blader' for assistance on this or any issue.