The main reason you won't find Li-ion D cells is that D cells are 1.5V, and Li-ion is 3.6V. You can find NiMH D cells, which are 1.2V, though these seem to have fallen out of favor. What application are you trying to solve?I've not had any luck in finding any sources (under 1000 pcs) for rechargable Li-ion cell in D size. Anyone have a lead?
These are new older 4C with 2" head, shortened, rethreaded, inside bored out (to fit protected 26650) and outside grooved incand M*g with "C" in front of serial number. (Thick wall tubes)5mega, running 2x protected cells are you using ML stock heavy coil tail contact spring?
Or do you machine a Cu disc, to fit on spring end, acting as a buffer against soft cathodes?