CELL EQUALIZATION TECHNIQUES.
Abstract
Charge control of nickel-cadmium cells was accomplished by means of a stabistor constructed of forward-biased diodes which, through the use of careful heat sink design bypasses most of the charge current around a cell when it becomes charged. A conduction type heat sink was designed and applied to the fabrication of cells of 6, 12 and 20 AH capacity designed to meet a cycle of 35 minutes, 75 percent discharge followed by 55 minutes charge over a range of -10 C and 50 C. It was demonstrated that a battery of secondary cells with stabistor charge control can be subjected to C/1 charge for 30 days without harmful effects. Studies of the effects of changes in ambient temperature on the operation of a stabistor/cell combination showed that the stabistor tends to compensate, to a large extent, for the decrease in cell charging efficiency with increasing temperature. Low-energy gap diodes and transistor circuits for reversal protection were found to have excessive forward leakage, causing rapid discharge of cells. A reed switch circuit was found satisfactory, but limited in current. Tests demonstrated that the voltage characteristic of a charging silver-cadmium cell causes proper operation of the stabistor.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 25, 1966
- Accession Number
- AD0482052
Entities
People
- James M Ball
- Richard Amsterdam