Archived posting to the Leica Users Group, 1999/08/02
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Gary- The thing about Ni-Cds is that they have an extremely low internal resistance. Most batteries or cells have a relatively high internal resisitance and when loaded, this resistance limits the amount of current available. Following Kirchoff's law, the interanl resistance 'drops' a certain amount of voltage potential at the terminals and so the device operates with a lower voltage. Ni-Cds- short the terminal, and the battery 'dumps' the current! Things get hot! I would imagine that the Leica folks are concerned that if their motors are loaded too severely, that the Ni-Cds would not load up and self limit the current, and the motors would burn up or at least suffer from overcurrent situations. If they are having 'electronic' problems, then the current limiting circuit might be one of the hold ups on development, though a lot of people have solved that problem years ago! Dan - ----- Original Message ----- From: Gary Klein <gklein@excel.net> To: Leica Users Group <leica-users-digest@mejac.palo-alto.ca.us> Sent: Monday, August 02, 1999 11:33 AM Subject: [Leica] Motor drive battery packs > I think what happened in the development of the Leica R8 motor drive is that > the engineers (I am sure the Leica engineers are very good ones to a fault) > are going nuts over the differences in motor drive speed when you use Nicads > vs alkalines vs lithiums. > > In my Nikon F3, I have the Nicad pack for the drive and have also used > alkalines with the standard battery pack. With the nicads film flies > through the camera. The rate on that camera with the mirror up is something > like 5.5 frames per second and 4.5 with the mirror operational. > > The camera is more responsive with the nicads, but I am sure Leica is > worried about long term survival of their motor. I think they are very gun > shy as they probably got burned by the previous supplier. All they have to > do is look at the F3 motor and do some stealing back technology. > > gck > > >