which charger goes with which battery?
Here's a list of the original batteries and chargers for each model:
7.2V NiCd Nikon Battery EN-1, charger: EH-1/EH-2 (Nikon E2 series)
7.2V Ni-MH Nikon Battery EN-3, charger: EH-3 (Nikon E3 series)
7.2 V NiCd Fujifilm battery BP-5D (Fujix DS-505(A)/515(A)), charger: Unknown (you can use Nikon's NiCd charger EH-1/EH-2)
7.2V Ni-MH Fujifilm Battery BP-D56 (Fujix DS-560/565), charger: Unknown (you can use a Nikon Ni-MH charger)
Again, you can use any of these batteries (EN-1, EN-3 and BP-D56) with any E/DS camera. Just make sure you have the correct charger (Ni-Mh charger for Ni-Mh batteries, and NiCd charger for NiCd batteries).
Since both Nikon and Fujifilm sold all the batteries and chargers using their own models names, there are several combinations that will work. For example, you can use Fujifilm's BP-D56 battery with Nikon's EH-3 charger.
And remember: All Ni-MH batteries (both Nikon and Fujifilm) can also use the Nikon D1 chargers MH-15 and MH-16.
Finally, you can also use Nikon's AC adapter ES-1 or Fujifilm's AC adapter AC-D56.
Hope this helps.