Fast charging nickel-metal hydride traction batteries

This paper describes the fast charge ability, or "fast rechargeability", of nominal 85 Ah Ni-MH modules under various fast charge conditions, includin g constant current (CC); typically 1-3C, and constant power (CP) regimes. O ur tests revealed that there is no apparent difference between CC and CP fa st charge regimes with respect to charge efficiency and time. Following the USABC Electric Vehicle Battery Test Procedures Manual (Revision 2, 1996), we demonstrated that we were able to return 40% state of charge (SOC) from 60% depth of discharge (DOD) to 20% DOD within 15 min. Most importantly, we found that the internal pressure of the cell is the most critical paramete r in the control of the fast charge process and the safe operation of the m odules. (C) 2001 Elsevier Science B.V. All rights reserved.