rechargable C maglites? Maglite only has one rechargable model: the magcharger.

If you use rechargable (NiMh or NiCa) batteries in your C maglite, it wouldn't be a problem if you use the proper Led upgrade module. Diffrent size maglite's have diffrent upgrade module: 3C/D maglites are 4.5 volts (3x1.5), a 4 C/D maglite 6 volts, etc. Rechargable NiMh and NiCa are lower in voltage (1.2V) versus the alkaline counterparts (1.5V), so you don't have to worry about frying a Led module. They a re bit expensive though! € 18.50 here: http://www.samenkopen.net/action_products/29627/571474
People have expresed concern about the cooling of the new Led modules from maglite. Normal Luxeon III usually have much larger coolsink mounted on there backs.