The best way to picture this is to remember that NiCD cell's reistance (R) increases when near full charge/fully charged. As a result, for a given current (I), and an increase in R, the voltage (V) drops...to the point that the algorythm shuts off the charge process (it varies from MFG to MFG, but ~8mV/cell, which is reduced as cell-count increases).
With NiMH cells, as their internal temperature increases, there is a reduction in resistance (up to a point). This is why those who employ NiMH for racing purposes (F5B/D cars, etc) like to operate the cells immediately off the charger (@ ~50-55C - FWIW can stand to hold in my hand a pack that is at ~60- 65C, but just barely). So, as a charger with a peak detect designed for NiCD charges a NiMH the temperature within the cell rises "after" reaching a fully charged state (now in overcharge), which pushes their internal resistance down, which moves further away from the peak detect V, which heats the cell(s) more, which...you get the picture I'm sure. The end result is cells that have eventually kicked off the peak detect, have been overcharged... Quoting Bill Swingle <[EMAIL PROTECTED]>: > >>Efficient cells > > Isn't the "peak" to which we're referring here dependant upon only the > battery chemistry? > Thus, a NiMH will always peak the same? > > The rate of charge does change the peak. Particularly the slope. Possibly > this is what they were relying upon to create some promotional verbiage? > > Bill Swingle > > RCSE-List facilities provided by Model Airplane News. Send "subscribe" and > "unsubscribe" requests to [EMAIL PROTECTED] Please note that > subscribe and unsubscribe messages must be sent in text only format with MIME > turned off. > Radius Systems Cogito Ergo Zoom RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off.
