They make a very abuse-tolerant battery, with a water wash and small stiff brush sufficent for monthly maintenance.
However, when I pulled the pack for a tractor repaint this summer, EVen though the nicads were inside an intact Elec-Trak battery bag, the KOH electrolyte that inEVitably vents out, encrusts and corrodes EVerything within reach had managed to migrate beyond the bag and turned a thick layer of POR-15 coating into a soupy black mess! I cleaned it up and repainted, without measurable losses, but am now going with lithium against antique metal and moving the nicads to other uses. Chris, have you found a good method of containing your nicads in the ET?