Christopher Zach mentioned putting together another pack of his nicad cells for a freshened ET. I'll second that notion, as I'm also still running 30 of the milspec bb600 30 Ah 1.2V cells from our 2005 group buy. These cells were used on the dragstrip in my Karmann Eclectric from 2005-2010, and have been on arguably tougher ET duty EVer since, getting covered with dust, DC dump-charged mid-mow from a 48V pack, and then run down again until the E14 tractor just crawls into the shed and gets recharged with a salvaged ferroresonant golf cart charger. I hose the pack down a couple times per year and top off the distilled water once per year and have only killed a few cells, always due to overheated loose connections or an interpack short caused by a buildup of conductive electrolyte on the cell tops. Like the Elec-Trak, these cells are simple and tough, and can last for decades with basic maintenance.
The one thing I've nEVer really solved is full containment of the vented KOH electrolyte, which is very high Ph so dissolves paint and causes corrosion in a jiffy. I tried the stout poly bags that Jim sells for pack isolation, but had to discard them after they became a soupy toxic mess with holes worn through the bottom from my pack jostling around over the rusty base. I suppose a fully welded plastic box liner or rubber pads plus the containment bag would be better. Anybody else found a good way to cope? I haven't tried a pad loaded with chemical buffer, as that would have to be acidic, and I'm not sure that fighting fire with fire is the right way to go atop antique steel.
Meanwhile, my I-5 rEVival with LFP cells remains a pretty museum piece in the corner of the garage, needing only some final wiring before the trusty rusty E14 can return to hibernation or get a rustoration.
Last note, these cells can be shipped by UPS, but are of course very heavy. SAFT America in Valdosta Georgia accepted my dead cells for free recycling at InMetCo in Pennsylvania, but I have to pay the shipping. (I've helped other NiCad users in the Seattle EV Association consolidate dead cells for a shipment.)
-Jay